Data communication method, communication system and mobile terminal

ABSTRACT

In a communications system which complies with LTE including a base station  2  which transmits data by using an OFDM (Orthogonal Frequency Division Multiplexing) method as a downlink access method, and a mobile terminal  3,  in a case in which an uplink scheduling request signal SR is transmitted by using an S-RACH when an Ack/Nack signal is being transmitted by using an Ack/Nack exclusive channel, the transmission of the Ack/Nack signal is stopped while the uplink scheduling request signal SR is transmitted.

FIELD OF THE INVENTION

The present invention relates to a communication system which is called“Long Term Evolution” (LTE), a mobile terminal which constructs thiscommunication system, and a communication method for an uplink controlsignal which this mobile terminal transmits to a base station.

BACKGROUND OF THE INVENTION

Commercial services which employ a W-CDMA (Wideband Code divisionMultiple Access) method which is included in communication methodscalled a third generation were started in Japan since 2001. Furthermore,a start of a service with HSDPA (High Speed Down Link Packet Access)which implements a further improvement in the speed of data transmissionusing downlinks (an individual data channel and an associated controlchannel) by adding a channel for packet transmission (HS-DSCH: HighSpeed-Downlink Shared Channel) to the downlinks has been planned. Inaddition, an HSUPA (High Speed Up Link Packet Access) method has alsobeen suggested and studied in order to speed up uplink datatransmission.

The W-CDMA is a communication method which was determined by the 3GPP(3rd Generation Partnership Project) which is the organization ofstandardization of mobile communication systems, and the technicalspecification of the release 6 has been being organized currently.

In the 3GPP, as a communication method different from the W-CDMA, a newcommunication method having a wireless section, which is referred to as“Long Term Evolution” (LTE), and a whole system structure including acore network, which is referred to as “System Architecture Evolution”(SAE), has been studied.

The LTE has an access method, a radio channel configuration, andprotocols which are different from those of the current W-CDMA(HSDPA/HSUPA). For example, while the W-CDMA uses, as its access method,code division multiple access (Code Division Multiple Access), the LTEuses, as its access method, OFDM (Orthogonal Frequency DivisionMultiplexing) for the downlink direction and uses SC-FDMA (Single CareerFrequency Division Multiple Access) for the uplink direction.Furthermore, while the W-CDMA has a bandwidth of 5 MHz, the LTE can havea bandwidth of 1.25/2.5/5/10/15/20 MHz. In addition, the LTE uses only apacket communication method, instead of a circuit switching method whichthe W-CDMA uses.

According to the LTE, because a communication system is constructedusing a new core network different from a core network (General PacketRadio System GPRS) which complies with the W-CDMA, the communicationsystem is defined as an independent radio access network which isseparate from a W-CDMA network. Therefore, in order to distinguish froma communication system which complies with the W-CDMA, in acommunication system which complies with the LTE, abase station (Basestation) which communicates with a mobile terminal UE (User Equipment)is called eNB (E-UTRAN NodeB, eNodeB, or eNode-B), a base stationcontrol apparatus (Radio Network Controller) which performs exchange ofcontrol data and user data with a plurality of base stations and iscalled an aGW (Access Gateway).

This communication system which complies with the LTE carries outpoint-to-multipoint (Point to Multipoint) communications, such as amulticast and broadcast type multimedia service called a E-MBMS (EvolvedMultimedia Broadcast Multicast Service), and also provides acommunication service such as a unicast (Unicast) service for eachmobile terminal among a plurality of mobile terminals.

In the case of the LTE, because no individual channels (DedicatedChannel and Dedicated Physical Channel) destined for each mobileterminal exist in transport channels and physical channels, transmissionof data to each mobile terminal is carried out by using a common channel(Shared channel), unlike in the case of the W-CDMA.

When receiving data, via a downlink, from a base station, a mobileterminal transmits a signal indicating whether the mobile terminal hasreceived the data perfectly, and a signal indicating either the qualityof the received data or the quality of the downlink communication pathto the base station via an uplink. The response signal indicatingwhether the mobile terminal could receive the data correctly from thebase station is referred to as an Ack/Nack, and the quality informationindicating the quality of the received data or the quality of thedownlink communication path is referred to as a CQI (Channel QualityIndicator).

An Ack/Nack is a signal with which, when the mobile terminal hasreceived downlink data, the mobile terminal notifies informationindicating whether the mobile terminal could receive the downlink datacorrectly to the base station, and the base station uses the Ack/Nackfor retransmission control.

A CQI is a signal with which the mobile terminal notifies the downlinkchannel's state (the communication path's state) which the mobileterminal has measured to the base station, and the base station uses theCQI for downlink scheduling. Furthermore, when data which the mobileterminal has to transmit to the base station occur, the mobile terminaltransmits a signal with which to make a request for allocation of uplinkradio resources to the base station. Such a request signal is called ascheduling request, an uplink resource request, or an uplink schedulingrequest signal (SR: Scheduling Request). The Ack/Nack, the CQI, and theSR as mentioned above are called “uplink L1/L2 control signals” (anL1/L2 control signaling).

FIG. 22 is an explanatory drawing for explaining uplink L1/L2 controlsignals.

As shown in FIG. 22, uplink L1/L2 control signals are roughly dividedinto two types of L1/L2 control signals. They are uplink-data-associatedL1/L2 control signals (a data-associated L1/L2 control signaling), anduplink-data-non-associated L1/L2 control signals (a data-non-associatedL1/L2 control signaling).

An uplink-data-associated L1/L2 control signal is information requiredfor uplink data transmission (reception by a base station), such as atransport format, and is transmitted together with uplink data.Uplink-data-non-associated L1/L2 control signals include an Ack/Nack anda CQI which are relevant to a downlink, and random access (RandomAccess) signals, such as a scheduling request (SR, UL SR) which istransmitted before uplink data transmission is started.

Although an Ack/Nack and a CQI are transmitted regardless of uplink datatransmission because they are relevant to a downlink, there is a case inwhich they are transmitted at the same time when uplink data aretransmitted. On the other hand, random access signals include asynchronous random access (Synchronous Random Access which is referredto as SRA from here on) signal and a non-synchronous random access(Non-Synchronous Random Access which is referred to as NSRA from hereon) signal.

An SRA is transmitted in a state in which uplink time synchronization isestablished, whereas an NSRA is transmitted in a state in which uplinktime synchronization is not established.

Not only uplink-data-associated L1/L2 control signals but also anAck/Nack and a CQI are transmitted in a state in which uplink timesynchronization is established. Hereafter, the fact that there is astate in which an Ack/Nack and/or a CQI, and an SRA in a case in whichno uplink data transmission is carried out are transmittedsimultaneously will be mentioned, and a problem with this state and asolution of this problem will be mentioned.

An uplink Ack/Nack and an uplink CQI are relevant to a downlink. Forallocation of an Ack/Nack and a CQI to physical resources to in the casein which no uplink data transmission is carried out, a method ofmonopolistically allocating one certain time-frequency region or amethod of monopolistically allocating a plurality of time-frequencyregions having separated narrow bands is used (for example, refer tononpatent reference 1).

Hereafter, these regions are referred to as an Ack/Nack exclusivechannel.

That is, in a state in which uplink data transmission is not performed,an Ack/Nack and a CQI are transmitted by using an Ack/Nack exclusivechannel.

In further explaining in detail, (1) in a case in which both an Ack/Nackand a CQI have to be transmitted, the Ack/Nack and the CQI aretransmitted by using an Ack/Nack exclusive channel, (2) in a case inwhich an Ack/Nack has to be transmitted, but a CQI does not have to betransmitted, the Ack/Nack is transmitted by using an Ack/Nack exclusivechannel, and (3) in a case in which an Ack/Nack does not have to betransmitted, but a CQI has to be transmitted, the CQI is transmitted byusing an Ack/Nack exclusive channel. It can also be considered that, (4)even in a case in which an Ack/Nack does not have to be transmitted, anda CQI does not have to be transmitted, an Ack/Nack exclusive channel isallocated to them. In this case, both no Ack/Nack and no CQI aretransmitted by using the above-mentioned channel.

FIG. 23 is an explanatory drawing showing radio resources to which anAck/Nack and a CQI are allocated in the case in which uplink datatransmission is carried out or in the case in which no uplink datatransmission is carried out. FIG. 23 shows the method ofmonopolistically allocating one certain time-frequency region.

An Ack/Nack and a CQI in the case in which no uplink data transmissionis carried out are allocated to a region having one or more subframeswith respect to time and are allocated to a region having one or moreresource units with respect to frequency. In contrast, uplink data, andan Ack/Nack and a CQI in the case in which transmission of either anuplink-data-associated L1/L2 control signal or the uplink data iscarried out are allocated to another region.

By allocating an Ack/Nack and a CQI in the case in which no uplink datatransmission is carried out, i.e., signals associated with only anAck/Nack and a CQI to a monopolistic region intended only for thesignals, a time during which the Ack/Nack and CQI signals aretransmitted can be increased, and therefore a large coverage can beacquired.

FIG. 24 is an explanatory drawing showing radio resources in which anAck/Nack and a CQI are allocated to an Ack/Nack exclusive channel. FIG.24 shows the method of monopolistically allocating a plurality oftime-frequency regions (A and B in FIG. 24) having separated narrowbands for an Ack/Nack and a CQI.

An Ack/Nack and a CQI in the case in which no uplink data transmissionis carried out are allocated to some separated regions in units of asubframe with respect to time and are allocated to some separatedregions in units of a subcarrier with respect to frequency. Byseparating the frequency region into some parts (e.g., A and B in FIG.24), a frequency diversity gain can be acquired.

When using either of the methods, an Ack/Nack and a CQI of one or moremobile terminals can be allocated to one region. It has been studied to,in order to implement a method of multiplexing an Ack/Nack and a CQI ofone or more mobile terminals into one region, establish theorthogonality of each mobile terminal by using FDM (Frequency DivisionMultiplex)/TDM (Time Division Multiplex)/CDM (Code Division Multiplex).In order to ensure the quality of reception of an Ack/Nack and a CQI bya base station, it has been studied to increase the power by carryingout repetition (repetition) transmission of the Ack/Nack and the CQI.More specifically, there are a method of repeatedly transmitting thesame subframe twice within one transmission time interval (TransmissionTime Interval TTI), a method of repeatedly including a bit of anAck/Nack and a bit of a CQI to a plurality of LBs (Long Block) in asubframe so as to transmit them, and so on.

A synchronous random access (Synchronous Random Access SRA) is a signalused for a scheduling request (SR) which a mobile terminal transmitsbefore starting uplink data transmission, which the mobile terminaltransmits when the mobile terminal is placed in a state in which uplinktime synchronization is established (in other words, the mobile terminalis placed in an Active mode). As a method of allocating an SRA tophysical resources, there is provided a method of monopolisticallyallocating one certain time-frequency region (Nonpatent reference 3:TR25.814V7.0.0). FIG. 25 is an explanatory drawing showing radioresources in which an uplink scheduling request signal is allocated toan S-RACH. FIG. 25 shows the method of monopolistically allocating onecertain time-frequency region.

An SRA is allocated to a region in units of a subframe with respect totime and is allocated to a region in units of one or more resource unitswith respect to frequency. Hereafter, these regions are referred to asan S-RACH (Synchronous Random Access CHannel). In contrast, uplink dataare allocated to other regions. Therefore, an SRA and data aremultiplexed with respect to either or both of time and frequency.

With which region a mobile terminal transmits an SRA is predetermined oris notified in advance from a base station. An SRA of one or more mobileterminals is allocated to one region. When transmissions of SRAs of aplurality of mobile terminals occur with an identical region, thesignals from the plurality of mobile terminals will collide with oneanother.

When the SRAs from the plurality of mobile terminals collide with oneanother and therefore the base station cannot receive them, each of theplurality of mobile terminals generally repeats transmission of its SRAagain with either or both of a different periodicity and a differentregion. In order to reduce the probability that SRAs from a plurality ofmobile terminals collide with one another, a method of establishing theorthogonality of each mobile terminal by using FDM/TDM/CDM has beenstudied.

Use of a scheduled channel has been also studied as allocation of asynchronous random access SRA to physical resources (nonpatent reference4).

A scheduled channel is scheduled to be allocated to each target mobileterminal, unlike a channel, such as an S-RACH, in which collision (orreferred to as competition) of signals from a plurality of mobileterminals is allowed. In this case, because a region which is allocatedin advance to each mobile terminal is decided, there is no competitionbetween signals from a plurality of mobile terminals, and thereforethere is no necessity to transmit, as an SR signal which each mobileterminal has transmitted, the ID number (the UE-ID) of each mobileterminal which is effective within the cell of the base station.Therefore, in a case in which an uplink SRA is transmitted by using ascheduled channel, the amount of information of the uplink SR signal canbe reduced.

A process of transmitting an Ack/Nack and a CQI, and an synchronousrandom access (an SR or the like) simultaneously in the case in which nouplink data transmission is carried out will be explained.

An uplink Ack/Nack and an uplink CQI are the ones which, when a mobileterminal is receiving downlink data from a base station, the mobileterminal transmits to the base station according to the status of thereception. In contrast, an SRA is the one which the mobile terminaltransmits to the base station for an SR or the like before startingtransmission of uplink data. Because the descriptions of these signalsare independent from one another, there can be a case in which themobile terminal transmits them simultaneously.

FIG. 26 shows an example in which a mobile terminal transmits anAck/Nack and an SRA simultaneously in the case in which the mobileterminal is not carrying out any uplink data transmission.

This example is a case in which transmission of uplink data occurs whilethe mobile terminal carries out continuous reception of downlink data.The mobile terminal is receiving downlink data continuously. The dataare demodulated and decoded in units of each TTI. The mobile terminaltransmits result information (Ack/Nack) indicating a result of judgmentof the reception to the base station according to the status of thereception of the downlink data. When receiving the transmission datanormally from the base station, the mobile terminal transmits an Acksignal to the base station. The base station which has received the Acktransmits new data next time. In contrast with this, when not being ableto receive the transmission data transmitted normally from the basestation, the mobile terminal transmits a Nack signal to the basestation. The base station which has received the Nack retransmits thedata which the mobile terminal was not able to receive normally to themobile terminal.

Allocation of the uplink Ack/Nack to physical resources is implementedby monopolistically allocating a plurality of time-frequency regionshaving separated narrow bands, as previously explained. Therefore, theuplink Ack/Nack is also transmitted continuously. In contrast, whenuplink data occurs in the mobile terminal, the mobile terminal transmitsa scheduling request SR to the base station before transmitting theuplink data. Allocation of the SR to physical resource is implemented bymonopolistically allocating one certain time-frequency region, aspreviously explained. Therefore, as shown in the figure, when uplinkdata occur at a certain time, an SR occurs with a short time delay.

When the base station is not able to receive the SR signal which themobile terminal has transmitted, the mobile terminal transmits the SRsignal again. As can be seen from the above explanation, there occurs astatus in which, when transmission of uplink data occurs while, forexample, a mobile terminal carries out continuous reception of downlinkdata, the mobile terminal has to transmit an uplink Ack/Nack and anuplink SRA simultaneously. Furthermore, even though the mobile terminaldoes not receive the downlink data continuously, but receives thedownlink data discontinuously, it is apparent that there may be a casein which the mobile terminal carries out the transmission of the uplinkSR signal simultaneously if the mobile terminal transmits the uplinkAck/Nack which is a response to the received data.

Similarly, it can be considered that, also when a scheduled channel isallocated as allocation of the scheduling request SR, which the mobileterminal transmits to the base station, to physical resources, thereoccurs a status in which the mobile terminal have to transmit the uplinkAck/Nack and the uplink SRA simultaneously.

Nonpatent reference 4 describes nothing about what type of channel isused as a scheduled channel and how to allocate a time-frequency regionas a physical resource. It is therefore understood that even if there isprovided, for example, a channel in which a 1-bit physical resourceintended only for a scheduling request SR is allocated, the mobileterminal has to transmit an uplink Ack/Nack continuously when carryingout continuous reception of downlink data, and therefore there occurs astatus in which, when transmission of uplink data occurs at that time,the mobile terminal has to transmit an uplink Ack/Nack and an uplink SRAsimultaneously.

Furthermore, the nonpatent reference 4 suggests nothing about “theproblems of the invention” and “the advantages of the invention” whichwill be shown in the specification of the present invention.

Nonpatent reference 5 discloses transmitting an uplink schedulingrequest by using an individual uplink control channel, such as anexisting channel (CQICH) for CQI transmission or an existing channel(ACHCH) for Ack/Nack transmission. The reference shows that, as aresult, a transmission procedure of transmitting an uplink schedulingrequest with little delay (Delay) can be established.

However, the nonpatent reference 5 suggests nothing about “the problemsof the invention” and “the advantages of the invention” which will beshown in the specification of the present invention.

The nonpatent reference 5 discloses only transmitting an uplinkscheduling request by using either a channel (CQICH) for CQItransmission or a channel (ACHCH) for Ack/Nack transmission, butdiscloses nothing about how to allocate the CQICH and the ACHCH, asphysical resources, to a time-frequency region. It is thereforeunderstood that even if a case in which an uplink scheduling request istransmitted by using, for example, a channel (CQICH) for CQItransmission, is considered, when a mobile terminal is carrying outcontinuous reception of downlink data, the mobile terminal has totransmit an uplink Ack/Nack continuously, and therefore there occurs astatus in which, when transmission of uplink data occurs at that time,the mobile terminal has to transmit an uplink Ack/Nack (ACHCH) and anuplink scheduling request (CQICH) simultaneously.

It is therefore understood that the nonpatent reference 5 does not solve“the problems of the invention” shown in the specification of thepresent invention.

-   [Nonpatent reference 1] 3GPP contributions R1-062741-   [Nonpatent reference 2] 3GPP contributions R1-062742-   [Nonpatent reference 3] 3GPP TR25.814V7.0.0-   [Nonpatent reference 4] 3GPP contributions R1-062719-   [Nonpatent reference 5] 3GPP contributions R1-062571

Because conventional communication systems which comply with the LTE areconstructed as mentioned above, an SC-FDMA (Single Career FrequencyDivision Multiple Access which is also referred to as DFT-spread OFDM)is used as an uplink access method. Because the SC-FDMA is singlecarrier transmission, compared with multi carrier transmission, such asOFDM, in which symbolic data are transmitted with them being piggybackedonto each subcarrier, the SC-FDMA has a feature of being able to reducethe PAPR (Peak to Average Power Ratio peak to average power ratio).Therefore, because the power consumption of a mobile terminal can bereduced at a time when the mobile terminal carries out transmission andthe transmit power which satisfies defined adjacent channel leakagepower can be increased, there is provided an advantage of widening thecell coverage. However, there may be a case in which a mobile terminalhas to simultaneously carry out a process of transmitting an uplinkAck/Nack and an uplink CQI by using an Ack/Nack exclusive channel and aprocess of transmitting an uplink scheduling request signal (SR) byusing an S-RACH or a scheduled channel, or a CQICH and an ACHCHaccording on its status. In this case, because those signals have nocorrelation among them, when transmitted simultaneously, they are nottransmitted with single carrier transmission, but are transmitted withmulti carrier transmission. In the case in which such signals having nocorrelation among them are transmitted simultaneously, the PAPR becomeshigh because the time waveforms of the transmission signals have a highpeak. A problem is that as the PAPR becomes high, the power consumptionof the mobile terminal increases and therefore the cell coverage becomesnarrow. A further problem is that as the PAPR becomes high, thosesignals become an interference wave to other mobile terminals and thecommunication system.

The present invention is made in order to solve the above-mentionedproblems, and it is therefore an object of the present invention toprovide a data communication method, a communication system, and amobile terminal which can prevent increase in the radio resources loaddue to temporary increase in the physical channels and can also reducethe PAPR (peak to average power ratio).

DISCLOSURE OF THE INVENTION

In accordance with the present invention, there is provided a datacommunication method with which a mobile terminal carries out a responsesignal transmission process of transmitting a response signal to a basestation by using an uplink control channel in an uplink direction fromthe mobile terminal to the base station, a scheduling request signaltransmission process of transmitting a scheduling request signal to thebase station by using a physical channel different from the uplinkcontrol channel when transmission data to be transmitted to the basestation occur, and a control process of, when a processing timing of theresponse signal transmission process coincides with that of thescheduling request signal transmission process, stopping the responsesignal transmission process during a time interval during which themobile terminal transmits the scheduling request signal.

As a result, because it is not necessary to use a multi carrier methodof simultaneously transmitting data associated with two physicalchannels (an Ack/Nack exclusive channel an S-RACH) which are allocatedto two types of bands, there is provided an advantage of being able toprevent the increase in the radio resource load of the communicationsystem due to temporary increase in the physical channels, and to reducethe PAPR (peak to average power ratio).

In accordance with the present invention, there is provided acommunications system in which a mobile terminal includes: atransmitting unit for transmitting a response signal to a base stationby using an uplink control channel in an uplink direction from themobile terminal to the base station, and for transmitting a schedulingrequest signal to the base station by using a physical channel differentfrom the uplink control channel when transmission data to be transmittedto the base station occur; and a control unit for, when a transmissiontiming of the response signal coincides with that of the schedulingrequest signal in the transmitting unit, stopping the transmissionprocess of transmitting the response signal during a time intervalduring which the transmitting unit transmits the scheduling requestsignal.

As a result, because it is not necessary to use a multi carrier methodof simultaneously transmitting data associated with two physicalchannels (an Ack/Nack exclusive channel an S-RACH) which are allocatedto two types of bands, there is provided an advantage of being able toprevent the increase in the radio resource load of the communicationsystem due to temporary increase in the physical channels, and to reducethe PAPR (peak to average power ratio).

In accordance with the present invention, there is provided a datacommunication method with which a mobile terminal carries out a controlsignal generation process of generating an uplink control signalincluding at least a response signal, while, when transmission data tobe transmitted to a base station occur, performing time divisionmultiplexing of a scheduling request signal and the response signal togenerate the uplink control signal, and a control signal transmissionprocess of transmitting a control signal including the uplink controlsignal generated through the control signal generation process to thebase station by using an uplink control channel in an uplink directionfrom the mobile terminal to the base station.

As a result, because it is not necessary to use a multi carrier methodof simultaneously transmitting data associated with two physicalchannels (an Ack/Nack exclusive channel an S-RACH) which are allocatedto two types of bands, there is provided an advantage of being able toprevent the increase in the radio resource load of the communicationsystem due to temporary increase in the physical channels, and to reducethe PAPR (peak to average power ratio).

In accordance with the present invention, there is provided a datacommunication method with which a mobile terminal selectively carriesout either a process of coding individual data by using a first code ora process of coding the individual data including a scheduling requestsignal by using a second code when transmission data to be transmittedthe base station occur, and also carries out a process of transmittingthe coded individual data by using an uplink common channel.

As a result, because it is not necessary to use a multi carrier methodof simultaneously transmitting data associated with two physicalchannels (an Ack/Nack exclusive channel an S-RACH) which are allocatedto two types of bands, there is provided an advantage of being able toprevent the increase in the radio resource load of the communicationsystem due to temporary increase in the physical channels, and to reducethe PAPR (peak to average power ratio).

In accordance with the present invention, there is provided a datacommunication method with which a mobile terminal carries out a controlsignal generation process of, when transmission data to be transmittedto a base station occur, performing time division multiplexing of atleast a scheduling request signal and a response signal to generate anuplink control signal, and a control signal transmission process oftransmitting a control signal including the uplink control signalgenerated through the control signal generation process to the basestation by using a random access channel which is a physical channel.

As a result, because it is not necessary to use a multi carrier methodof simultaneously transmitting data associated with two physicalchannels (an Ack/Nack exclusive channel an S-RACH) which are allocatedto two types of bands, there is provided an advantage of being able toprevent the increase in the radio resource load of the communicationsystem due to temporary increase in the physical channels, and to reducethe PAPR (peak to average power ratio).

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is an explanatory drawing showing the structure of a mobilecommunication system mobile communication system which complies withLTE;

FIG. 2 is an explanatory drawing showing the structure of channels foruse with the communications system which complies with LTE;

FIG. 3 is a block diagram showing the structure of a mobile terminal;

FIG. 4 is a block diagram showing the structure of a base station;

FIG. 5 is an explanatory drawing for explaining radio resources whichare allocated to an Ack/Nack exclusive channel and an S-RACH fortransmission of an uplink scheduling request signal SR;

FIG. 6 is a flow chart explaining processing carried out by a mobileterminal, including up to a process of transmitting an uplink schedulingrequest signal;

FIG. 7 is a flow chart explaining a series of processes including fromthe process of transmitting an uplink scheduling request signal up to aprocess of starting transmission of uplink data;

FIG. 7 is a flow chart explaining the series of processes including fromthe process of transmitting an uplink scheduling request signal up tothe process of starting transmission of uplink data;

FIG. 9 is an explanatory drawing for explaining examples of mapping ofAck/Nack symbols to be transmitted by using an Ack/Nack exclusivechannel;

FIG. 10 is an explanatory drawing for explaining examples of mapping ofAck/Nack symbols to be transmitted by using an Ack/Nack exclusivechannel;

FIG. 11 is an explanatory drawing for explaining radio resources whichare allocated to an Ack/Nack exclusive channel and an S-RACH fortransmission of an uplink scheduling request signal SR;

FIG. 12 is an explanatory drawing for explaining examples of mapping ofAck/Nack symbols to be transmitted by using an Ack/Nack exclusivechannel;

FIG. 13 is a flow chart explaining processing carried out by a mobileterminal, including up to a process of transmitting an uplink schedulingrequest signal;

FIG. 14 is an explanatory drawing for explaining an example of mappingof an uplink scheduling request signal which is transmitted by using anAck/Nack exclusive channel;

FIG. 15 is a flow chart for explaining processing carried out by amobile terminal which transmits an uplink scheduling request signal, andprocessing carried out by a base station which receives the uplinkscheduling request signal;

FIG. 16 is a flow chart for explaining processing carried out by amobile terminal which transmits an uplink scheduling request signal, andprocessing carried out by a base station which receives the uplinkscheduling request signal;

FIG. 17 is an explanatory drawing showing allocation of radio resourcesof a UL-SCH and an RACH;

FIG. 18 is a flow chart explaining processing carried out by a mobileterminal, including up to a process of transmitting an uplink schedulingrequest signal;

FIG. 19 is an explanatory drawing showing radio resources in which apreamble and a message, an Ack/Nack, a CQI, and an SR are mapped onto anS-RACH;

FIG. 20 is an explanatory drawing showing radio resources in which apreamble and a message, an Ack/Nack, a CQI, and an SR are mapped onto anS-RACH;

FIG. 21 is an explanatory drawing showing radio resources in which apreamble and a message, an Ack/Nack, a CQI, and an SR are mapped onto anS-RACH;

FIG. 22 is an explanatory drawing for explaining an uplink L1/L2 controlsignal;

FIG. 23 is an explanatory drawing showing radio resources to which anAck/Nack and a CQI are allocated in the case in which uplink datatransmission is carried out or in the case in which no uplink datatransmission is carried out;

FIG. 24 is an explanatory drawing showing radio resources in which anAck/Nack and a CQI are allocated to an Ack/Nack exclusive channel;

FIG. 25 is an explanatory drawing showing radio resources in which anuplink scheduling request signal is allocated to an S-RACH;

FIG. 26 is an explanatory drawing showing an example in which a mobileterminal transmits an Ack/Nack and an SRA simultaneously in a case inwhich the mobile terminal is not carrying out any uplink datatransmission;

FIG. 27 is an explanatory drawing for explaining an example of mappingof an uplink scheduling request signal which is transmitted by using anAck/Nack exclusive channel;

FIG. 28 is a sequence diagram in a case of a first example of a setting;

FIG. 29 is a flow diagram of processing carried out by a mobile terminalin the case of the first example of the setting;

FIG. 30 is a flow diagram of processing carried out by a base station inthe case of the first example of the setting;

FIG. 31 is a sequence diagram in a case of a second example of thesetting;

FIG. 32 is a flow diagram of processing carried out by a mobile terminalin the case of the second example of the setting;

FIG. 33 is a flow diagram of processing carried out by a base station inthe case of the second example of the setting;

FIG. 34 is a detailed block diagram of a mobile terminal which transmitsan uplink scheduling request signal;

FIG. 35 is an explanatory drawing of allocation of radio resources for aSounding RS during transmission of uplink data in Embodiment 7;

FIG. 36 is a concrete sequence diagram in a case in which an uplinktransmission request occurs in a state where no data communications arecarried out via both an uplink and a downlink;

FIG. 37 is a flow chart showing a flow in a case in which a transmissionrequest occurs in a state in which a mobile station is synchronized witha base station and is not carrying out transmission of uplink data;

FIG. 38 is an explanatory drawing showing a method of allocating radioresources in a case in which a base station sets up a plurality of BWsfor a usual Sounding RS, and the circumstances of allocation of radioresources to a mobile terminal UE1;

FIG. 39 is a flow chart showing a setting of the BW of a Sounding RS bya base station eNodeB;

FIG. 40 is a flow chart showing a judging method in a case in which thebase station eNodeB selects the BW;

FIG. 41 is a flow chart showing a judging method in a case in which amobile terminal selects the BW;

FIG. 42 is an explanatory drawing of allocation of radio resources in aplurality of UEs in one UE group;

FIG. 43 is an explanatory drawing in a case of setting up a Sounding RSregion for each UE group;

FIG. 44 is an explanatory drawing of a generation method of generating areference signal for sounding having the functions of an uplinkscheduling request signal;

FIG. 45 is a diagram of sequences between a mobile terminal and a basestation;

FIG. 46 is an explanatory drawing of an allocation method of allocatinga pilot for sounding and a mobile-terminal-specific code in a case inwhich a mobile terminal transmits a reference signal for sounding;

FIG. 47 is an explanatory drawing showing a pilot pattern in which apart of a sounding pilot is symbols for scheduling request;

FIG. 48 is a diagram of sequences between a mobile terminal and a basestation;

FIG. 49 is an explanatory drawing of an example of generation of areference signal for sounding;

FIG. 50 is a diagram of sequences between a mobile terminal and a basestation;

FIG. 51 is an explanatory drawing of an example of generation of areference signal for sounding;

FIG. 52 is a diagram of sequences between a mobile terminal and a basestation;

FIG. 53 is an explanatory drawing in a case in which a reference signalfor sounding is transmitted at certain time intervals;

FIG. 54 is an explanatory drawing in a case in which a reference signalfor sounding which is transmitted at certain time intervals serves as anuplink scheduling request signal;

FIG. 55 is an explanatory drawing of a time-frequency resource in a casein which there is an Ack/Nack exclusive channel region;

FIG. 56 is an explanatory drawing of a time-frequency resource in a caseof allocating a region of RS for sounding to all of the entire band ofthe system;

FIG. 57 is an explanatory drawing of a time-frequency resource;

FIG. 58 is an explanatory drawing of a time-frequency resource;

FIG. 59 is an explanatory drawing of transmission symbol mapping in amobile terminal in a case of transmitting an uplink scheduling requestsignal with a region for sounding RS;

FIG. 60 is an explanatory drawing of a transmission signal of a mobileterminal when a scheduling request occurs;

FIG. 61 is an explanatory drawing of a transmission signal of a mobileterminal when a scheduling request occurs;

FIG. 62 is a diagram of sequences between a mobile terminal and a basestation;

FIG. 63 is an explanatory drawing of a transmission signal of a mobileterminal when an uplink scheduling request occurs;

FIG. 64 is a diagram of sequences between a mobile terminal and a basestation;

FIG. 65 is an explanatory drawing of a transmission signal of a mobileterminal when an uplink scheduling request occurs; and

FIG. 66 is a diagram of sequences between a mobile terminal and a basestation.

PREFERRED EMBODIMENTS OF THE INVENTION

Hereafter, in order to explain this invention in greater detail, thepreferred embodiments of the present invention will be described withreference to the accompanying drawings.

Embodiment 1

FIG. 1 is an explanatory drawing showing the structure of a mobilecommunication system which complies with LTE. In FIG. 1, an aGW 1performs transmission and reception of control data and user data with aplurality of base stations (eNodeB) 2, and a base station 2 transmitsand receives data to and from a plurality of mobile terminals 3. Betweena base station 2 and a mobile terminal 3, broadcast information,information used for processing a call, individual control data,individual user data, control data for E-MBMS, user data, and so on aretransmitted. It has also been studied that base stations 2 communicatewith each other.

A base station 2 has uplink and downlink schedulers. These schedulers ofa base station 2 enable transmission and reception of data between thebase station 2 and each mobile terminal 3, and carry out scheduling forimprovements in the throughput of each mobile terminal 3 and that of thewhole mobile communication system.

A E-MBMS provides a broadcast type point-to-multipoint (Point toMultipoint P to M) communication service with which data are transmittedat a time from a certain base station toward a plurality of mobileterminals. Concretely, an information service, such as news or weatherforecast, and a large-volume broadcast service, such as mobile TV, havebeen studied.

The aGW 1 communicates with a service center 5 via a PDN 4 (Packet DataNetwork).

The service center 5 stores and distributes a content used for providinga service for users. A content provider transmits E-MBMS data, such asmobile TV broadcast data, to the service center 5. The service center 5stores the E-MBMS data therein and also transmits the E-MBMS data tobase stations 2 via the PDN 4 and the aGW 1.

FIG. 2 is an explanatory drawing showing the structure of channels.Mapping of logical channels (Logical channels) and transport channels(Transport channels) is shown in FIG. 2.

The logical channels are classified according to the functions andlogical characteristics of transmission signals. The transport channelsare classified according to transmission forms. Broadcast information ispiggybacked onto a BCCH (Broadcast Control Channel). A BCCH is mapped toa BCH (Broadcast Channel) and is transmitted from a base station tomobile terminals.

Information used for processing a call is piggybacked onto a PCCH(Paging Control Channel). A PCCH is mapped to a PCH (Paging Channel) andis transmitted from a base station to mobile terminals in the cell ofthe base station. Individual control data destined for each mobileterminal are piggybacked onto a DCCH (Dedicated Control Channel).

Individual user data destined for each mobile terminal are piggybackedonto a DTCH (Dedicated Traffic Channel). A DCCH and a DTCH are mapped toa DL-SCH (Downlink Shared Channel), and are transmitted individuallyfrom a base station to each mobile terminal. In contrast with this, itis individually transmitted from each mobile terminal to abase stationby using a UL-SCH (Uplink Shared Channel).

A DL-SCH and a UL-SCH are shared channels (Shared Channels).

Control data for E-MBMS and user data are piggybacked onto an MCCH(Multicast Control Channel) and an MTCH (Multicast Traffic Channel),respectively, and are mapped to a DL-SCH or an MCH (Multicast Channel)and are transmitted from a base station to a mobile terminal.

A connection request signal from a mobile terminal, e.g., a schedulingrequest signal SR is transmitted from each mobile terminal to a basestation by using a random access channel (Random Access Channel RACH).An S-RACH is one of RACHs.

FIG. 3 is a block diagram showing the structure of a mobile terminal. Atransmitting process of the mobile terminal 3 is carried out as follows.

First, control data from a protocol processing unit 6 and user data froman application unit 7 are stored in a transmission data buffer unit 8.

The data stored in the transmission data buffer unit 8 are delivered toan encoder unit 9, and the encoder unit performs an encoding process,such as an error correction, on the data. There can exist data on whichno encoding process is performed and which are directly outputted fromthe transmission data buffer unit 8 to a modulating unit 10.

The modulating unit 10 performs a modulation process on the data onwhich the encoding process has been performed by the encoder unit 9.After the modulated data are converted into a baseband signal, thisbaseband signal is outputted to a frequency converting unit 11 and isthen converted into a signal having a radio transmit frequency. Afterthat, the transmission signal is transmitted to a base station 2 from anantenna 12.

A receiving process of the mobile terminal 3 is carried out as follows.A radio signal from the base station 2 is received by the antenna 12.The received signal having a radio receive frequency is converted into abaseband signal by the frequency converting unit 11, and a demodulatingunit 13 performs a demodulation process on the baseband signal. Datawhich the demodulating unit obtains after demodulating the basebandsignal are delivered to a decoder unit 14, and the decoder unit performsa decoding process, such as an error correction, on the data. Controldata among the decoded data are delivered to the protocol processingunit 6, while user data among the decoded data are delivered to theapplication unit 7. The series of transmission and reception processesof the mobile terminal is controlled by a control unit 15.

FIG. 4 is a block diagram showing the structure of a base station. Atransmitting process of the base station 2 is carried out as follows.

An aGW communication unit 16 transmits and receives data between thebase station 2 and an aGW 1. An other base station communication unit 17transmits and receives data to and from another base station.

Each of the aGW communication unit 16 and the other base stationcommunication unit 17 receives and sends information from and to aprotocol processing unit 18. Control data from the protocol processingunit 18 and user data from the aGW communication unit 16 and the otherbase station communication unit 17 are stored in a transmission databuffer unit 19.

The data stored in the transmission data buffer unit 19 are delivered toan encoder unit 20, and the encoder unit performs an encoding process,such as an error correction, on the data. There can exist data on whichno encoding process is performed and which are directly outputted fromthe transmission data buffer unit 19 to a modulating unit 21. Themodulating unit 21 performs a modulation process on the data on whichthe encoding process has been performed by the encoder unit.

After the modulated data are converted into a baseband signal, thisbaseband signal is outputted to a frequency converting unit 22 and isthen converted into a signal having a radio transmit frequency. Afterthat, the transmission signal is transmitted from an antenna 23 to oneor more mobile terminals 1.

A receiving process of the base station 2 is carried out as follows.

A radio signal from one or more mobile terminals 3 is received by theantenna 23. The received signal having a radio receive frequency isconverted into a baseband signal by the frequency converting unit 22,and a demodulating unit 24 performs a demodulation process on thebaseband signal. Data which the demodulating unit obtains afterdemodulating the baseband signal are delivered to a decoder unit 25, andthe decoder unit performs a decoding process, such as an errorcorrection, on the data. Control data among the decoded data aredelivered to the protocol processing unit 18, and user data among thedecoded data are delivered to the aGW communication unit 16 and theother base station communication unit 17. The series of transmission andreception processes of the base station 2 is controlled by a controlunit 26.

Hereafter, the operation of a mobile terminal in accordance with thepresent invention will be explained.

When a mobile terminal is not performing uplink data transmission and isreceiving downlink data, the mobile terminal transmits an Ack/Nacksignal indicating the result of the reception of the downlink data(whether the mobile terminal has received the data properly) to the basestation by using an Ack/Nack exclusive channel.

The mobile terminal also transmits a downlink communication path quality(CQI) signal for the downlink scheduling by the base station, as well asthe Ack/Nack signal indicating the result of the reception of thedownlink data, to the base station by using the Ack/Nack exclusivechannel.

Furthermore, regardless of whether the mobile terminal has received thedownlink data, in order to enable the downlink scheduling by the basestation or maintain the synchronization between the base station and themobile terminal, the mobile terminal transmits a CQI signal to the basestation by using the Ack/Nack exclusive channel.

When the mobile terminal starts transmission of uplink data in a statein which the mobile terminal transmits an Ack/Nack signal and/or a CQIsignal to the base station, as mentioned, the mobile terminal has totransmit an uplink scheduling request signal SR independently from theabove-mentioned Ack/Nack and/or the above-mentioned CQI to the basestation. In this embodiment, a method of, when transmitting an uplinkscheduling request signal SR to the base station by using a physicalchannel (S-RACH) different from the Ack/Nack exclusive channel,transmitting the uplink scheduling request signal by using an SC-FDMAmethod which implements a wider coverage and a lower PAPR will beexplained.

In this Embodiment 1, in a case in which a mobile terminal desires tostart transmission of uplink data in a state in which the mobileterminal transmits an Ack/Nack signal and/or a CQI signal by using anuplink Ack/Nack exclusive channel while receiving downlink data withoutperforming transmission of uplink data, the mobile terminal transmits anuplink scheduling request signal SR for setting up a channel for uplinkdata transmission by using a physical channel (in this Embodiment 1, byusing an S-RACH) to which a frequency band different from that of theAck/Nack exclusive channel is allocated.

At that time, the mobile terminal does not use a multi carrier method ofsimultaneously transmitting data associated with two physical channelswhich are allocated to two types of bands, respectively, the mobileterminal does not transmit an Ack/Nack signal and/or a CQI signal byusing the Ack/Nack exclusive channel (DTX Discontinuous Transmission)while transmitting an SR (preamble/message) which the mobile terminaltemporarily transmits to the base station when starting transmission ofuplink data.

As a result, increase in the radio resource load on the system due totemporary increase in the physical channels of one mobile terminal canbe prevented, while transmission with a single carrier method whichguarantees a low PAPR can be implemented.

FIG. 5 is an explanatory drawing for explaining radio resources whichare allocated to an Ack/Nack exclusive channel and an S-RACH fortransmission of an uplink scheduling request signal SR. FIG. 6 is a flowchart explaining processing carried out by a mobile terminal, includingup to a process of transmitting an uplink scheduling request signal.

FIGS. 7 and 8 are flow charts explaining a series of processes includingfrom the process of transmitting an uplink scheduling request signal upto a process of starting transmission of uplink data. In FIG. 5, it isassumed that at the same time when the mobile terminal UE1 is notcarrying out transmission of uplink data, such as user data, but isreceiving only downlink data, the mobile terminal is transmitting anAck/Nack and/or a CQI to these received data by using an Ack/Nackexclusive channel.

The modulating unit 10 of the mobile terminal shown in FIG. 3 performs aCDM multiplexing process (can alternatively perform an FDM multiplexingprocess or a TDM multiplexing process), which is specific to the mobileterminal, on the Ack/Nack signal, and transmits the Ack/Nack signal byusing the Ack/Nack exclusive channel. Therefore, there can be a case inwhich the mobile terminal UE1 transmits the Ack/Nack signal continuouslywith respect to time by using the Ack/Nack exclusive channel.

In this case, when an uplink data transmission request in ST601 of FIG.6 occurs (if Yes in ST601), the mobile terminal, in ST602, checks thereceiving state of the downlink data (DL data).

In this Embodiment 1, because the mobile terminal is receiving thedownlink data, the mobile terminal advances to ST604 in which the mobileterminal determines the timing at which the mobile terminal transmits anuplink scheduling request signal SR (preamble or/and message) by usingan S-RACH. If the mobile terminal is not receiving any downlink data andthe synchronization with the base station is not established (if No inST602), the mobile terminal, in ST603, carries out an algorithm oftransmitting an uplink scheduling request signal SR by using a physicalchannel called a Non-S-RACH.

After, in ST604, determining the transmission timing of the uplinkscheduling request signal SR, at the same time when the mobile terminalUE1 transmits the uplink scheduling request signal SR by using theS-RACH, the mobile terminal, in ST605, stops the transmission of apredetermined Ack/Nack symbol (or LB) of the uplink Ack/Nack exclusivechannel or a CQI symbol (or LB), which the mobile terminal wasoriginally scheduled to transmit at the same timing, and suspends thetransmission while the mobile terminal transmits the uplink schedulingrequest signal SR (symbol DTX or DTX of LB). This stop (DTX) of thetransmission of the Ack/Nack symbol is performed by the modulating unit10 under the control of the control unit 15.

FIG. 5 shows an example of the allocation of radio resources to anS-RACH which is a physical channel via which an uplink schedulingrequest signal SR is transmitted, and an Ack/Nack exclusive channel.

In FIG. 5, the radio resources are divided into a plurality oftime-frequency regions. In each time-frequency region, the time axis isdivided into units of each subframe (=0.5 ms), and the frequency axis isdivided into units having different bands according to the amount oftransmission data associated with the physical channel.

In the allocation of the radio resources according to this Embodiment 1,the S-RACH and the channel for uplink data transmission usetime-frequency unit regions having the same size, respectively, whereasthe Ack/Nack exclusive channel uses a frequency band unit regionnarrower than the time-frequency unit regions (the same time division).A subframe 1 of one subcarrier in the Ack/Nack exclusive channel iscomprised of six long blocks (Long Blocks LB1 to LB6) and two shortblocks (Short Blocks SB, small blocks).

A symbol for physical channel synchronization (a symbol fordemodulation) is included in a short block SB. While the mobile terminalUE1 transmits the uplink scheduling request signal SR with the length ofone subframe by using the time-frequency region of the S-RACH which isallocated as shown in FIG. 5, the mobile terminal stops the modulationand transmission of the symbol data of the long blocks LB1 to LB6 andthe two short blocks SB which are currently allocated to the Ack/Nackexclusive channel (the mobile terminal carries out DTX).

However, because, in the next subframe 2, there is no transmission ofthe uplink scheduling request signal SR using the S-RACH and there isalso no transmission of uplink data such as user data, the mobileterminal transmits symbol data (LB2-1 to LB2-6) for the subframe 2 byusing the Ack/Nack exclusive channel. Furthermore, in the next subframe(a subframe 1 during TTI No.2), an uplink scheduling request signal SRfrom another mobile terminal UE occurs, an S-RACH for this SR isallocated to a time-frequency region which exists in a frequency banddifferent from that of the mobile terminal UE1.

In this case, the S-RACH of the other mobile terminal UE is transmitted,and Ack/Nack symbol data and/or CQI symbol data from the mobile terminalUE1 during this subframe interval are transmitted by using the Ack/Nackexclusive channel. The sequence including from the transmission of anuplink scheduling request signal SR by using the S-RACH up to the uplinkdata transmission is shown in FIGS. 7 and 8.

FIG. 7 shows a flow chart in a case (ST701) in which the mobile terminaltransmits an uplink scheduling request signal SR (preamble and message)in only one step.

FIG. 8 shows a flow chart in a case (ST801 and ST803) in which themobile terminal transmits an uplink scheduling request signal SR bysequentially transmitting its preamble (preamble) and its message(message) in two steps.

In FIG. 7, after the mobile terminal notifies the uplink schedulingrequest to the base station with the preamble and the message, themobile terminal receives information “uplink data resource allocation(Uplink Data Resource Allocation)” about allocation of radio resourcesfor uplink data transmission and timing by using a downlink L1/L2control signal from the base station.

In FIG. 8, the mobile terminal receives “scheduling request resourceallocation (SR Resourece Allocation)” after transmitting the preamble,and, after notifying a message part of the scheduling request to thebase station by using a resource which is allocated thereto with thescheduling request resource allocation, receives information (UplinkData Resource Allocation) about radio resources allocation for uplinkdata transmission and timing by using a downlink L1/L2 control signalfrom the base station.

The mobile terminal then starts transmission of uplink data by using aUL-SCH (Uplink Shared channel). In this Embodiment 1, the example inwhich one subframe is allocated to transmission of an uplink schedulingrequest signal SR is explained. However, because there is a case inwhich a preamble and a message are sent at a time during a longtransmission time, as shown in FIG. 7, and a case in which they are sentat two times during short transmission time, as shown in FIG. 8, thelength of a transmission time during which an Ack/Nack cannot betransmitted, and the occurrence frequency can be changed according tothe length and frequency of the transmission time of the uplinkscheduling request signal SR.

The structure of long blocks and short blocks in a subframe shown inFIG. 5 is only an example, and, even if the structure of the subframechanges, the concept of the present invention can be applied.

Hereafter, the preamble and message of an uplink scheduling requestsignal SR will be explained. It is considered that, for example, a“random ID (random ID (UE ID))” which is specific identifyinginformation for identifying the terminal is allocated to the preamble.As the message, the amount of uplink transmission data (a buffer statein the UE), the QoS of the uplink transmission data, or a transmissionpower margin of the terminal, in addition to the “UE ID” previouslyshown, can be considered.

In conventional communication methods (FDMA, TDMA, and CDMA), a stop(DTX) of transmission of symbols via an uplink provides an advantage ofreducing the power consumption of a mobile terminal, reducing thehighest transmit power of the mobile terminal to within a power rangeindicated by a base station, and also reducing the transmit power of thewhole system to within a fixed range. In contrast, by using the methodof stopping transmission of symbols (DTX) in accordance with the presentinvention, because, for an uplink, not only the PAPR in the mobileterminal can be reduced, but single carrier transmission can be carriedout, unlike in the case of using DTX of a conventional communicationmethod, the scale of the implementation of the modulation anddemodulation processes can be reduced in both the mobile terminal andthe base station, and the processing load on the whole system can bereduced compared with the case of using a multi carrier transmissionmethod.

As mentioned above, by using Embodiment 1, there can be provided anadvantage of, in a case in which a mobile terminal is not carrying outtransmission of uplink data, but is receiving downlink data, enablingthe mobile terminal which has to transmit an uplink scheduling requestsignal SR together with an Ack/Nack to perform the transmission of thesesignals simultaneously without increasing the PAPR in the mobileterminal.

In contrast, there can be a case in which in the mobile communicationsystem, even when a mobile terminal does not receive downlink data, anAck/Nack exclusive channel is allocated to the mobile terminal.

More specifically, there can be considered a case in which even whenthere exist no downlink data in a base station, in order to preparefuture downlink scheduling or maintain the synchronization between thebase station and a mobile terminal, the result (CQI) of measurement ofthe quality of a downlink communication path is notified from the mobileterminal to the base station. Also in such a case, there can beconsidered a case in which the transmission of the CQI using an Ack/Nackexclusive channel and an uplink scheduling request signal SR occursimultaneously. In such a mobile communication system, it is preferablethat when performing judgment as shown in ST602, a mobile terminaljudges whether or not an Ack/Nack exclusive channel is allocatedthereto. In addition, even a mobile communication system in which when amobile terminal does not receive downlink data no Ack/Nack exclusivechannel is allocated to the mobile terminal can adopt this judgment.

Embodiment 2

In above-mentioned Embodiment 1, in a case in which a mobile terminaltransmits an uplink scheduling request signal SR by using an S-RACHwhile transmitting an Ack/Nack signal and/or a CQI signal by using anAck/Nack exclusive channel, the mobile terminal stops the transmissionof the Ack/Nack signal and/or the CQI signal while transmitting theuplink scheduling request signal SR.

By stopping the transmission of the Ack/Nack signal and/or the CQIsignal while transmitting the uplink scheduling request signal SR, themobile terminal does not have to use a multi carrier method with whichto simultaneously transmit data associated with the two physicalchannels (the Ack/Nack exclusive channel and the S-RACH) which areallocated to two types of bands, respectively. Therefore, increase inthe radio resources load on the communication system due to temporaryincrease in the physical channels can be prevented, and transmissionwith a single carrier method which guarantees a low PAPR can beimplemented.

In contrast, in Embodiment 2 which will be explained hereafter, amapping method for an Ack/Nack exclusive channel of, when performing astop (DTX) of transmission of an Ack/Nack symbol, preventing a badinfluence from being exerted upon the performance of communications ofsymbols on the Ack/Nack exclusive channel will be explained.

In Embodiment 1, the processing including from the process oftransmitting an uplink scheduling request signal SR by using an S-RACHup to a process of transmitting uplink data is explained with referenceto FIG. 52. More specifically, the transmission of an uplink schedulingrequest signal SR (a preamble or/and a message) includes a case, asshown in FIG. 7, in which a long transmission time is needed in order tosend the preamble and the message at a time and a case, as shown in FIG.8, in which the preamble is transmitted at a time and the message istransmitted at another time and therefore their respective transmissiontime become short.

In the case in which the transmission time of an uplink schedulingrequest signal SR is long, the time during which an Ack/Nack and/or aCQI cannot be transmitted (the DTX of the Ack/Nack symbol and/or the CQIsymbol) becomes long, whereas in the case in which the transmission timeof an uplink scheduling request signal SR are short, the time intervalduring which an Ack/Nack and/or a CQI cannot be transmitted becomesshort. For each of the cases, a method of preventing the degradation ofthe communication quality due to occurrence of errors in thetransmission of the Ack/Nack symbol information and/or the CQI symbolinformation during the time during which the uplink scheduling requestsignal SR is transmitted will be explained hereafter.

First, the process in the case of FIG. 7 will be explained. Because thepreamble and the message are collectively transmitted at a time in thetransmission of the uplink scheduling request signal SR shown in FIG. 7,the time interval during which the Ack/Nack and/or the CQI cannot betransmitted becomes long, and can have a length of about one subframe asshown in FIG. 5. In order to prevent the degradation in thecommunication quality due to errors in the transmission of the Ack/Nacksymbol information and/or the CQI symbol information which can occurduring this time interval, in accordance with this Embodiment 2, apattern of symbols to be sent by using the Ack/Nack exclusive channel ismapped in such a way that a pattern having a length of one subframe isrepeated twice and is updated during each transmission time interval(TTI).

Furthermore, in order to ensure communication quality, a symbol patternhaving a length of one subframe is formed to be a combination of symbolsin which important information (higher-order bits) are given a higherpriority and the number of repetitions of the important information isincreased. Concrete examples of the mapping of symbol information whichis to be transmitted by using an Ack/Nack exclusive channel are shown inFIGS. 9 and 10.

FIG. 9 is an explanatory drawing explaining examples of the mapping ofAck/Nack symbols to be transmitted by using an Ack/Nack exclusivechannel. FIG. 9 shows an example of the mapping of symbols to theAck/Nack exclusive channel, which has been proposed by the 3GPP (3rdGeneration Partnership Project) until now (refer to the nonpatentreference 2).

For each of a case in which only Ack/Nack symbols are mapped to longblocks LB (FIG. 9( a)), a case in which only CQI symbols are mapped tolong blocks (FIG. 9( b)), and a case in which CQI symbols and Ack/Nacksymbols are multiplexed and are mapped to long blocks LB (FIG. 9( c)), asymbol mapping structure with a transmission time interval length (TTI)is shown.

A symbol pattern which is proposed in this Embodiment 2 is formed insuch a way that even in a case in which an Ack/Nack and/or a CQI cannotbe transmitted for a long period of time (=1 subframe), a symbol patternhaving a length of one subframe is repeated twice within 1 TTI for thepurpose of preventing occurrence of errors in the transmission of theAck/Nack and/or the CQI, thereby improving the communication quality.

In the symbol pattern shown in FIG. 9 in the case of CQI symbols, forone subframe A, CQI1, CQI2, CQI3, CQI4, CQI5, and CQI1 are mapped tolong blocks, whereas for one subframe B, CQI2, CQI3, CQI4, CQI1, CQI2,and CQI1 are mapped to long blocks, and the CQI symbols are not arrangedwith the same symbol pattern in the subframes.

Therefore, when, for example, the one subframe A is DTXed, CQI5 is nottransmitted once (one LB) during 1 TTI. Also in the symbol pattern inwhich CQIs and Acks/Nacks are multiplexed with respect to time, they arenot arranged with the same symbol pattern in both the one subframe A andthe one subframe B.

A mapping example of mapping the CQI symbols and a mapping example ofmultiplexing and mapping the CQI and the Ack/Nack, which are proposed bythe present invention, are shown in FIG. 10.

First, in the mapping example of mapping the CQI symbols of FIG. 10( a),the same symbol mapping pattern is repeated in both a first subframe(single sub-frame A) and a second subframe (single sub-frame B) within 1TTI. Furthermore, in the mapping of the symbols to each subframe length,symbols with a higher priority (i.e., symbols showing a higher-orderdigit of the CQI: in this example, CQI1) are repeated a larger number oftimes.

Furthermore, also in the mapping example of multiplexing and mapping theCQI symbols and the Ack/Nack symbol of FIG. 10( b), the same symbolmapping pattern is repeated in both a first subframe (single sub-frameA) and a second subframe (single sub-frame B) within 1 TTI, and, in themapping of the symbols to each subframe length, symbols with a higherpriority (the Ack/Nack and so on) are placed in a vicinity of a shortblock SB.

In this Embodiment 2, an Ack/Nack and the higher-order bits of a CQI(CQI1 is the most significant bit) are considered as symbols having ahigher priority. An Ack/Nack indicates the result of reception ofdownlink data, and therefore there arises a problem that retransmissionof corresponding packet data occurs when this bit cannot be receivedproperly by the base station. It is therefore necessary to increase thepriority of the Ack/Nack in the symbol arrangement. It is furthernecessary to place the higher-order ones of the CQI bits indicating thereception state of the downlink data on a priority basis so as to enablethe base station to cope with transmission errors and so on.

Thus, it is not necessary to limit the mapping pattern in the symbolmapping method of taking into consideration a risk of the Ack/Nackinformation not being transmitted while the uplink scheduling requestsignal SR is transmitted and the importance of the symbols to thepattern of FIG. 10 which is explained in this Embodiment 2.

Even though the symbol mapping is not performed as shown in FIG. 10,this Embodiment 2 can be implemented. Therefore, the concept about thesymbol mapping will be mentioned hereafter.

(1) Repeat symbols having a higher priority a larger number of times.(2) Place symbols having a higher priority in a vicinity of a shortblock SB.

In general, an Ack/Nack and the higher-order bits of a CQI (CQI1 is themost significant bit) are symbols having a higher priority.

An Ack/Nack indicates the result of reception of downlink data, andtherefore there arises a problem that, when this symbol cannot bereceived properly by the base station, retransmission of thecorresponding packet data occurs and the throughput of the downlink datafalls as a result. It is therefore necessary to increase the priority ofthe Ack/Nack in the symbol arrangement.

Also in the case of the higher-order ones of the CQI bits indicating thestate of the reception of the downlink data, when a transmission erroroccurs, the erroneous difference between the downlink communication pathquality which is measured by the mobile terminal and the downlinkcommunication path quality which the base station has received becomeslarge, and therefore appropriate scheduling cannot be carried out by thebase station and this results in reduction in the downlink throughput ofthe whole mobile communications system. It is therefore necessary toincrease the priority of the higher-order ones of the CQI bitsindicating the state of the reception of the downlink data in the symbolarrangement.

The priority of the Ack/Nack and that of the CQI depend on the desirederror rates of their respective signals.

Because increase in the number of repetitions (repetition) can increasethe receive power of the base station, the larger number of repetitions(repetition) a symbol has the more rarely an error occurs in the symbol.

Because it can be considered that a short block is used for phasecompensation when receiving the short block and then demodulating theshort block, the phase compensation is carried out more correctly as thedifference between the transmission timing of the short block and thatof the corresponding symbol decreases. Therefore, an error occurs morerarely in a symbol which is placed nearer to a short block. Somepredetermined patterns exist in the mapping of the symbols of Ack/Nackinformation (an Ack/Nack and/or a CQI), and the mobile station canselect one pattern from among the predetermined patterns, one patterncan be selected and notified by the base station, or one pattern can bedynamically allocated to the mobile station. As previously explained,when transmission of an Ack/Nack symbol and/or CQI symbols using anAck/Nack exclusive channel cannot be carried out temporarily for a longperiod of time (=during one subframe) because of transmission of anuplink scheduling request signal SR by using an S-RACH, an transmissionerror can be preventing from occurring in the information symbols of theAck/Nack exclusive channel and therefore high communication quality canbe maintained.

Next, a case in which the transmission time during which an uplinkscheduling request signal SR is transmitted once is sufficiently short,like the sequence of FIG. 8, will be explained.

In a case in which a mobile terminal, in ST605 of FIG. 6, transmits anuplink scheduling request signal SR, as shown in the flow chart of FIG.8, by dividing it into a preamble and a message or sending the preambleand the message of a small size together, the time interval during whichthe mobile terminal transmits the uplink scheduling request signal SRbecomes short. Therefore, the transmission stop time interval duringwhich transmission of an Ack/Nack symbol and/or a CQI symbol in theAck/Nack exclusive channel is stopped during the transmission of theuplink scheduling request signal SR also becomes short.

An example of how, in such a case, the S-RACH used for the transmissionof the uplink scheduling request signal SR and the Ack/Nack exclusivechannel are allocated in time-frequency is shown in FIG. 11.

Because the amount of information of the uplink scheduling requestsignal SR in the sequence diagram of FIG. 8 is sufficiently small, inFIG. 11, a region to which the S-RACH of the mobile terminal UE1 isallocated in time-frequency is only one leading data symbol blockincluded in one time-frequency unit region. An Ack/Nack symbol or a CQIsymbol which is transmitted at the same timing as this block is a symbolin a long block LB1 of the Ack/Nack exclusive channel. While the uplinkscheduling request signal SR using the S-RACH of the mobile terminal UE1is transmitted, the Ack/Nack information symbol or the CQI symbol in theblock which is the long block LB1 is not transmitted.

FIG. 12 is an explanatory drawing for explaining examples of the mappingof an Ack/Nack symbol and CQI symbols which are transmitted by using theAck/Nack exclusive channel.

Unlike FIG. 10, FIG. 12 shows cases in each of which different symbolsare mapped in a first subframe (one sub-frame A) and a second subframe(one sub-frame B) within 1 TTI, respectively, and either the Ack/Nack orhigher-order CQI bits having a higher priority are placed a largernumber of repetitions within the TTI.

As shown in FIG. 12( a), in a case in which only CQI symbols aretransmitted, when transmission of an uplink scheduling request signal SRoccurs, a symbol CQI1 having a higher priority is allocated to theposition of a long block LB (e.g., LB1) having a possibility of notbeing transmitted and the same symbol CQI1 is also allocated to the nextlong block LB2.

As a result, even in a case in which transmission of an uplinkscheduling request signal SR occurs, the most important symbol CQI1 canbe transmitted with the second long block LB2, and, even in a case inwhich no transmission of an uplink scheduling request signal SR occurs,the degradation in the quality at the time of occurrence of acommunication error can be prevented by transmitting the most importantsymbol CQI1 four times.

Furthermore, in a case in which the CQI symbols and the Ack/Nack symbolare multiplexed and mapped, as shown in FIG. 12( b), even whentransmission of an uplink scheduling request signal SR occurs throughallocation of a low-priority symbol CQI5 to the position of an LB (LB1)having a possibility of not being transmitted, and the CQI5 symbolcannot be transmitted, other symbols having a higher priority can besent without their repetition numbers being reduced, and therefore thecommunication quality can be maintained.

It is not necessary to limit the mapping pattern in the symbol mappingmethod according to the importance of the symbols to the pattern whichis explained in this Embodiment 2. Because the concept of the symbolmapping is already explained, the explanation of this concept will beomitted hereafter. Either the mobile terminal or the base station canselect one pattern from among some predetermined patterns of the mappingof the symbols of Ack/Nack information (an Ack/Nack and/or a CQI), orone of them can be dynamically selected and allocated to the mobileterminal.

As a case in which a region to which the S-RACH of the mobile terminalUE1 is allocated in time-frequency is only a part of data symbol blockswith respect to time, as shown in FIG. 11, there can be not only a casein which the information which is to be transmitted by using the S-RACHas shown in the flow chart of FIG. 8, but also a case in which theamount of information of the uplink scheduling request signal SR islarge as shown in the flow chart of FIG. 7.

In this case, the uplink scheduling request signal can be sent in asmall amount of time by allocating the S-RACH to the time-frequencyregion whose band is extended in the frequency direction, andtransmitting the uplink scheduling request signal by using the S-RACH.More specifically, compared with the case of allocation of FIG. 11,either a wider time-frequency region in the frequency direction or aplurality of time-frequency unit regions which are continuous in thefrequency direction are allocated to the transmission of the uplinkscheduling request signal SR.

Embodiment 1 and Embodiment 2 are based on the CDM multiplexing of theAck/Nack information which is carried out for each mobile terminal inthe Ack/Nack exclusive channel. As an alternative, there can be anothermethod of carrying out TDM multiplexing or FDM multiplexing of thepieces of Ack/Nack information about a plurality of mobile terminals.Also in such a case, the invention explained in above-mentionedEmbodiment 1 can be applied.

By doing in the above-mentioned way, also in a case in which an uplinkAck/Nack symbol and/or CQI symbols which are allocated to the sametiming as the time-frequency region to which the symbols of the uplinktransmission request signal SR are allocated with the S-RACH cannot bemodulated and transmitted (DTX) during the transmission time of theuplink scheduling request signal SR, there can be provided an advantageof being able to use the radio resources effectively and to maintain thecommunication quality of the uplink or reduce the degradation in thecommunication quality of the uplink to a minimum.

Embodiment 3

In above-mentioned Embodiment 1, by stopping transmission of an Ack/Nacksignal and/or a CQI signal while transmitting an uplink schedulingrequest signal SR by using an S-RACH, and by no using a multi carriermethod with which to simultaneously transmit data associated with thetwo physical channels (the Ack/Nack exclusive channel and the S-RACH)which are allocated to two types of bands, respectively, increase in theradio resources load on the communication system due to temporaryincrease in the physical channels can be prevented, and transmissionwith a single carrier method which guarantees a low PAPR can beimplemented.

In this Embodiment 3, a method of implementing transmission using anSC-FDMA method which implements a wider coverage and a lower PAPR (peakto average power ratio) by transmitting an Ack/Nack and/or a CQI and anuplink scheduling request signal SR by using an identical physicalchannel will be explained hereafter.

In accordance with this Embodiment 3, a mobile terminal transmits anuplink scheduling request signal SR by mapping the uplink schedulingrequest signal SR to an Ack/Nack exclusive channel instead of an S-RACH.By transmitting an uplink scheduling request signal SR by using anAck/Nack exclusive channel, increase in the radio resources load on thecommunication system due to temporary increase in the physical channelscan be prevented, and transmission with a single carrier method whichguarantees a low PAPR can be implemented. As a result, even when thenumber of control signals (L1/L2 control signalings) which have to betemporarily transmitted increases in a certain mobile terminal, increasein the radio resources load on the communication system can beprevented, and transmission with a single carrier method whichguarantees a low PAPR and high communication quality can be implemented.

In this case, the Ack/Nack exclusive channel is a scheduled channel forwhich radio resources are scheduled in advance. As mentioned above, inthe nonpatent reference 4, allocation of an synchronous random accessSRA to a scheduled channel is studied. However, because the nonpatentreference 4 describes nothing about what type of channel is used as thescheduled channel and how a time-frequency region is allocated as aphysical resource, in a case in which there is disposed a channel towhich a 1-bit physical resource used for a scheduling request SR isallocated to a time-frequency region different from the Ack/Nackexclusive channel, a status in which an uplink Ack/Nack and/or a CQI andan uplink SR have to be transmitted simultaneously occurs, and thesesignals are transmitted simultaneously with respect to time. In thiscase, because they are not transmitted with single carrier transmission,but are transmitted with multi carrier transmission, there arises aproblem that the PAPR increases.

In order to solve this problem, in accordance with this Embodiment 3, amobile terminal transmits an uplink scheduling request signal SR bymapping an Ack/Nack and a CQI with the uplink scheduling request signalSR, to an Ack/Nack exclusive channel.

An important thing to satisfy request for a single carrier transmissionfrom a mobile terminal is that the mobile terminal transmits all of an“Ack/Nack”, a “CQI”, and an “uplink scheduling request signal SR”, whichare signals having a possibility of having to be transmittedsimultaneously, by using an Ack/Nack exclusive channel in a state inwhich uplink time synchronization is established and the mobile terminalis not transmitting uplink data. By transmitting an Ack/Nack and a CQIwith an uplink scheduling request signal SR, by using an Ack/Nackexclusive channel, increase in the radio resources load on thecommunication system due to temporary increase in the physical channelscan be prevented, and transmission with a single carrier method whichguarantees a low PAPR can be implemented.

As a result, even when the number of control signals (L1/L2 controlsignalings) which has to be temporarily transmitted increases in acertain mobile terminal, increase in the radio resources load on thecommunication system can be prevented, and transmission with a singlecarrier method which guarantees a low PAPR and high communicationquality can be implemented.

FIG. 13 is a flow chart for explaining processing carried out by amobile terminal, the processing including up to a process oftransmitting an uplink scheduling request signal. FIG. 14 is anexplanatory drawing for explaining an example of mapping of an uplinkscheduling request signal which is transmitted by using an Ack/Nackexclusive channel.

Hereafter, the operation of a mobile terminal in accordance withEmbodiment 3 of the present invention will be explained with referenceto FIG. 13. In FIG. 13, because the same reference numerals as thoseshown in FIG. 6 denote the same components or like components, theexplanation of the components will be omitted hereafter.

A mobile terminal is not carrying out uplink user data transmission,and, at the same time when receiving downlink data, is transmitting, viaan uplink, an Ack/Nack and/or a CQI to the received data by using aphysical channel for an Ack/Nack and/or a CQI.

For the Ack/Nack exclusive channel, multiplexing of signals from mobileterminals is carried out by using either one of a CDM method, an FDMmethod, and a TDM method. When a request for transmission of uplink dataoccurs in the mobile terminal (ST601), the state of the reception of thedownlink data is checked in ST602.

In this Embodiment 3, because the mobile terminal is receiving thedownlink data, the mobile terminal advances to ST1301 in which themobile terminal transmits Ack/Nack information with an uplink schedulingrequest signal SR (only a part corresponding to a preamble or a partcorresponding to the preamble and a message), by using the Ack/Nackexclusive channel.

The sequence including from the transmission in ST1301 of the uplinkscheduling request signal SR up to the transmission of the uplink datais shown in FIG. 8. In a case in which the information size of theuplink scheduling request signal SR is small and the transmission timeis short, transmitting the uplink scheduling request signal SR by usingthe Ack/Nack exclusive channel is very effective from the viewpoint ofthe two following aspects: the efficiency of use of radio resources; andthe attainment of the communication quality of transmission (an L1/L2control signaling) of an L1/L2 control signal having a small size, likean Ack/Nack or an uplink scheduling request signal SR.

A time-frequency region having a length of one subframe in the Ack/Nackexclusive channel is comprised of six data symbol blocks which arecalled long blocks LB and symbol blocks for physical channelsynchronization which are called short blocks SB.

In this Embodiment 3, an example of the mapping of symbols at the timeof carrying out multiplexing of an uplink scheduling request signal SR,Ack/Nack information and/or CQI information within a time-frequencyregion of 1 TTI (=two subframes) with a predetermined positionalrelationship will be shown.

FIG. 14 is an example of the symbol mapping in a case in which CQIinformation and Ack/Nack information are multiplexed, and an uplinkscheduling request signal SR is further allocated to these pieces ofmultiplexed information. In this case, it is assumed that the Ack/Nack,the CQI, and the uplink scheduling request signal SR are multiplexed,and are mapped and updated in units of 1 TTI.

First, the uplink scheduling request (UL scheduling request) is mappedto a leading symbol block (LB1) within the time-frequency region havinga length of a transmission time interval (TTI) (=a length of twosubframes). The number of times that the uplink scheduling requestsignal SR is mapped and transmitted is one time/two subframes at thefastest rate. The description of the SR symbol is 1 bit long, and isinformation indicating either with request or without request.

Even though the symbol mapping is not carried out as shown in FIG. 14,this Embodiment 3 can be implemented. Therefore, the concept about thesymbol mapping will be mentioned hereafter.

(1) Repeat symbols having a higher priority a larger number of times.(2) Place symbols having a higher priority in a vicinity of a shortblock SB.

In general, an Ack/Nack, the higher-order bits of a CQI (CQI1 is themost significant bit), and an uplink scheduling request signal SR aresymbols having a higher priority.

An Ack/Nack indicates the result of reception of downlink data, andtherefore there arises a problem that, when this symbol cannot bereceived properly by the base station, retransmission of thecorresponding packet data occurs and the throughput of the downlink datafalls as a result. It is therefore necessary to increase the priority ofthe Ack/Nack in the symbol arrangement.

Also in the case of the higher-order ones of the CQI bits indicating thestate of the reception of the downlink data, when a transmission erroroccurs, the erroneous difference between the downlink communication pathquality which is measured by the mobile terminal and the downlinkcommunication path quality which the base station has received becomeslarge, and therefore appropriate scheduling cannot be carried out by thebase station and this results in reduction in the downlink throughput ofthe whole mobile communications system. It is therefore necessary toincrease the priority of the higher-order ones of the CQI bitsindicating the reception state of the downlink data in the symbolarrangement.

Furthermore, a case in which an uplink scheduling request signal SR isaccidentally received by the base station will be considered. When thebase station erroneously receives “presence” of an uplink schedulingrequest SR from a mobile terminal even though the mobile terminal shows“absence” of the uplink scheduling request SR, an unnecessary uplinkresource is allocated to the mobile terminal and hence the radioresource goes to waste.

In contrast, when the base station erroneously receives “absence” of anuplink scheduling request SR from a mobile terminal even though themobile terminal shows “presence” of the uplink scheduling request SR,there arises a problem that the mobile terminal has to retransmit theuplink scheduling request SR and the uplink throughput decreases as aresult.

The priorities of the Ack/Nack, the CQI, and the uplink schedulingrequest SR depend on their error rates.

Because increase in the number of repetitions (repetition) can increasethe receive power of the base station, the larger number of repetitions(repetition) a symbol has the more rarely an error occurs in the symbol.

Because it can be considered that a short block is used for phasecompensation when receiving data and then performing demodulation of thedata, the phase compensation is carried out more correctly as thedifference between the transmission timing of the short block and thatof the corresponding symbol decreases. Therefore, an error occurs morerarely in a symbol which is placed nearer to a short block.

In the explanation of the concept of the symbol mapping, which is madeuntil now, the case in which the multiplexing of a CQI and an Ack/Nackin an Ack/Nack exclusive channel is carried out by using the TDM methodis shown. Even in a case in which the multiplexing is carried out byusing another method, the concept of the above-mentioned symbol mappingcan be applied as the method of mapping an uplink scheduling requestsignal SR.

Furthermore, an uplink scheduling request signal SR has a value which isdefined as follows: “with request=(‘1’)” and “without request=(‘0’)”, asmentioned above. However, the definition is not limited to this example,and, for example, an uplink scheduling request signal SR canalternatively have a value which is defined as follows: “withrequest=(‘0’)” and without request=(‘1’)”. Further speaking, an uplinkscheduling request signal SR has only to show the presence or absence ofan uplink scheduling request.

There can be considered the two following examples of the setting of thevalue of this bit.

In the first example of the setting, when there is no uplink schedulingrequest signal SR, 0 is always transmitted. In contrast, in a case inwhich the mobile terminal transmits an uplink scheduling request signalSR, as shown in the flow chart of FIG. 8, the mobile terminal transmits“with request (=‘1’)”, and then transmits 0 during the next transmissiontime interval (TTI).

If there does not occur any receiving error, when “uplink data resourceallocation (Uplink Data Resource Allocation)” which the base stationought to have transmitted to the mobile station does not arrive thereat,the mobile terminal judges that an receiving error has occurred in thebase station, and then transmits the uplink scheduling request signal SRindicating “with request (‘1’)” again.

The first example of the setting will be explained in greater detailwith reference to FIGS. 28, 29, and 30.

FIG. 28 is a sequence diagram, and FIG. 29 is a flow diagram ofprocessing carried out by the mobile terminal. FIG. 30 is a flow diagramof processing carried out by the base station.

In FIG. 28, a time T shows a time limit (an upper limit) by which themobile terminal has to receive uplink resource allocation made by thebase station, and the mobile terminal uses a timer or the like in orderto implement the time T.

The operation of the first example of the setting will be explained bymainly referring to FIG. 29.

First, a case in which no receiving error occurs when the base stationreceives an uplink scheduling request signal SR will be explained. As asequence diagram, FIG. 28( i) shows the case in which no receiving erroroccurs.

The mobile terminal, in ST2901, judges whether a request fortransmission of uplink data has occurred. When a request fortransmission of uplink data has occurred, the mobile terminal advancesto ST2902. In contrast, when no request for transmission of uplink datahas occurred, the mobile terminal returns to the judgment of ST2901.

The mobile terminal, in ST2902, sets up information indicating thepresence of an uplink scheduling request (UL Scheduling request=“1”currently allocated to LB1 in FIG. 14) in the Ack/Nack exclusivechannel.

The mobile terminal then, in ST2903, transmits the informationindicating the “presence” of uplink scheduling by using the Ack/Nackexclusive channel. This step corresponds to ST2801 in FIG. 28.

After transmitting the information indicating the “presence” of uplinkscheduling by using the Ack/Nack exclusive channel, the mobile terminal,in ST2904, sets up information indicating the absence of an uplinkscheduling request (UL Scheduling request=“0” currently allocated to LB1in FIG. 14) in the Ack/Nack exclusive channel.

The mobile terminal, in ST2905, judges whether the mobile terminal hasreceived uplink data resource allocation “Uplink Data ResourceAllocation” from the base station. That is, the mobile terminal judgeswhether the mobile terminal has received uplink transmission allocationfrom the base station.

When, in ST2905, has received uplink data resource allocation, themobile terminal advances to ST2906. This step corresponds to ST2804 inFIG. 28. The mobile terminal, in ST2906, transmits uplink data accordingto the allocation from the base station.

In contrast, when, in ST2905, has not received uplink data resourceallocation, the mobile terminal advances to ST2907. The mobile terminal,in ST2907, judges whether the current time exceeds the time limit bywhich the mobile terminal has to receive “Uplink Data ResourceAllocation” from the base station. More specifically, the mobileterminal judges whether the time which has elapsed since the mobileterminal transmitted the information indicating the “presence of anuplink scheduling request signal SR exceeds the time T as shown in FIG.28.

When, in ST2905, the elapsed time does not exceed the time T, the mobileterminal advances to ST2908. The mobile terminal, in ST2908, transmitsthe information indicating the “absence” of uplink scheduling by usingthe Ack/Nack exclusive channel (UL Scheduling request=“0” currentlyallocated to LB1 in FIG. 14).

After, in ST2908, transmitting the information indicating the “absence”of uplink scheduling by using the Ack/Nack exclusive channel, the mobileterminal returns to the judgment of ST2905. This step corresponds toST2802 and ST2803 in FIG. 28.

Next, a case in which an receiving error occurs when the base stationreceives an uplink scheduling request signal SR will be explained. As asequence diagram, FIG. 28( ii) shows the case in which a receiving erroroccurs.

Because the explanation of the steps of ST2901 to ST2906 is the same asthat in the above-mentioned case in which no receiving error occurs, theexplanation will be omitted.

The mobile terminal, in ST2907, judges whether the current time exceedsthe time limit by which the mobile terminal has to receive “Uplink DataResource Allocation” from the base station, like in the above-mentionedcase in which no receiving error occurs. More specifically, the mobileterminal judges whether the time which has elapsed since the mobileterminal transmitted the information indicating the “presence” of anuplink scheduling request signal SR exceeds the time T as shown in FIG.28.

In this case, as shown in FIG. 28( ii), an receiving error has occurredin the information indicating the presence or absence of an uplinkscheduling request currently allocated, in ST2807, to the Ack/Nackexclusive channel. Therefore, at the timing (time ‘“t”’ of (ii) of FIG.28) at which the mobile terminal should have originally received “UplinkData Resource Allocation” from the base station, the mobile terminaldoes not accept any uplink transmission allocation from the basestation. As a result, the mobile terminal, in ST2907, judges that thetime which has elapsed since the mobile terminal, in ST2811 of FIG. 28,transmitted the information indicating the “presence” of an uplinkscheduling request signal SR exceeds the time T.

In this case, the mobile terminal returns to ST2902, sets up informationindicating the presence of an uplink scheduling request (UL Schedulingrequest=“1” currently allocated to LB1 in FIG. 14) in the Ack/Nackexclusive channel, and then retransmits the uplink scheduling requestsignal SR (ST2903) This step corresponds to ST2811 in FIG. 28.

Next, a flow of processing performed by the base station in the firstexample of the setting will be explained with reference to FIG. 30.

The base station, in step ST3001, judges whether the informationindicating the presence or absence of an uplink scheduling requestcurrently allocated to the Ack/Nack exclusive channel in ST3001 showsthe “presence.” When the information indicates the “absence,” the basestation returns to the judgment of ST3001.

When the base station, in step ST3001, judges that the informationindicates the “presence”, the base station performs an uplink schedulingprocess for the mobile terminal which, in step ST3002, has transmittedthe uplink scheduling request thereto by using the Ack/Nack exclusivechannel. This step corresponds to ST2801 or ST2811 in FIG. 28.

In order to perform uplink transmission allocation for the mobileterminal, the base station, in ST3003, transmits the result as “UplinkData Resource Allocation.” This step corresponds to ST2804 or ST2814 inFIG. 28.

In the second example of the setting, when not receiving any uplinkscheduling request signal SR, the base station always transmits 0, likein the case of the first example of the setting. In contrast, in theflowchart of FIG. 8, when the mobile terminal transmits an uplinkscheduling request signal SR, the mobile terminal continues transmittingthe information indicating “the presence of a request (=‘1’)” until“Uplink Data Resource Allocation” is transmitted thereto from the basestation, and, after receiving “Uplink Data Resource Allocation”, themobile terminal transmits the information indicating “the absence of arequest (=‘0’)”.

The second example of the setting will be explained in greater detailwith reference to FIGS. 31, 32, and 33.

FIG. 31 is a sequence diagram, and FIG. 32 is a flow diagram showingprocessing carried out by the mobile terminal. FIG. 33 is a flow diagramshowing processing carried out by the base station.

The operation of the second example of the setting will be explained bymainly referring to FIG. 32.

First, a case in which no receiving error occurs when the base stationreceives an uplink scheduling request signal SR will be explained. As asequence diagram, FIG. 31( i) shows the case in which no receiving erroroccurs.

The mobile terminal, in ST3201, judges whether a request fortransmission of uplink data has occurred. When a request fortransmission of uplink data has occurred, the mobile terminal advancesto ST3202. In contrast, when no request for transmission of uplink datahas occurred, the mobile terminal returns to the judgment of ST3201.

The mobile terminal, in ST3202, sets up information indicating thepresence of an uplink scheduling request (UL Scheduling request=“1”currently allocated to LB1 in FIG. 14) in the Ack/Nack exclusivechannel.

The mobile terminal then, in ST3203, transmits an uplink schedulingrequest by using the Ack/Nack exclusive channel. This step correspondsto ST3101 in FIG. 31.

The mobile terminal, in ST3204, judges whether the mobile terminal hasreceived “uplink data resource allocation (Uplink Data ResourceAllocation)” from the base station. That is, the mobile terminal judgeswhether the mobile terminal has received uplink transmission allocationfrom the base station.

When, in ST3204, has received uplink transmission allocation, the mobileterminal advances to ST3205. In contrast, when has not received uplinktransmission allocation, the mobile terminal returns to ST3202. Thisstep corresponds to ST3104 in FIG. 31.

The mobile terminal, in ST3205, sets up information indicating theabsence of an uplink scheduling request (UL Scheduling request=“0”currently allocated to LB1 in FIG. 14) in the Ack/Nack exclusivechannel. This step corresponds to ST3105 in FIG. 31.

The mobile terminal, in ST3206, transmits uplink data according to theallocation from the base station.

Next, a case in which a receiving error occurs when the base stationreceives an uplink scheduling request signal SR will be explained. As asequence diagram, FIG. 31( ii) shows the case in which a receiving erroroccurs.

Because the flow of the processing carried out by the mobile terminal inthis case is the same as that in the above-mentioned case in which noreceiving error occurs, the flow will be omitted.

The case (ii) shown in FIG. 31 will be explained.

A receiving error occurs in the information indicating the presence orabsence of an uplink scheduling request currently allocated, in ST3107,to the Ack/Nack exclusive channel. Therefore, at the timing (time ‘“t”’in the case (ii) of FIG. 31) at which the mobile terminal should haveoriginally received “Uplink Data Resource Allocation” from the basestation, the mobile terminal does not accept any uplink transmissionallocation from the base station.

However, in the second example of the setting, following the step ofST3107, the mobile terminal, also in ST3108, transmits the informationindicating the presence of an uplink scheduling request (UL Schedulingrequest=“1” currently allocated to LB1 in FIG. 14) by using the Ack/Nackexclusive channel. Therefore, when normally receiving the informationindicating the presence or absence of an uplink scheduling requestcurrently allocated to the Ack/Nack exclusive channel transmitted inST3108, the base station, in ST3111, transmits “Uplink Data ResourceAllocation.” That is, the mobile terminal receives the uplinktransmission allocation from the base station.

Next, a flow of processing carried out by the base station in the secondexample of the setting will be explained with reference to FIG. 33.

The base station, in step ST3301, judges whether the informationindicating the presence or absence of an uplink scheduling requestcurrently allocated to the Ack/Nack exclusive channel shows the“presence”. When the information indicates the “absence,” the basestation returns to the judgment of ST3301.

When the base station, in step ST3301, judges that the informationindicates the “presence,” the base station, in ST3302, judges whether ornot the base station is performing an uplink scheduling process for themobile terminal.

When, in ST3302, judging that the base station is performing an uplinkscheduling process for the mobile terminal (corresponding to ST3102,ST3103, ST3109, and ST3110 in FIG. 31), the base station advances toST3303. The base station, in ST3303, continues performing the uplinkscheduling process which the base station has been performing.

In contrast, when, in ST3302, judging that the base station is notperforming any uplink scheduling process for the mobile terminal(corresponding to ST3101 and ST3108 in FIG. 31), the base stationadvances to ST3304. The base station, in ST3304, starts performing anuplink scheduling process for the mobile terminal.

When, in ST3303 or ST3304, completing the uplink scheduling process forthe mobile terminal, the base station, in ST3305, transmits the resultof the process as “Uplink Data Resource Allocation” in order to performuplink transmission allocation for the mobile terminal. This stepcorresponds to ST3104 or ST3111 in FIG. 31.

The advantages of the first example of the setting and the secondexample of the setting will be explained.

Compared with the second example of the setting, the merits of the firstexample of the setting can be provided as follows:

(1) Because, when receiving an uplink scheduling request by using theAck/Nack exclusive channel, the base station does not have to judgewhether or not the base station is performing an uplink schedulingprocess for the mobile terminal (ST3302 in FIG. 33), the processingcarried out by the base station can be simplified.

Compared with the first example of the setting, the merits of the secondexample of the setting can be provided as follows:

(1) When a receiving error occurs in the information indicating thepresence or absence of an uplink scheduling request currently allocatedto the Ack/Nack exclusive channel, the time which has elapsed until themobile terminal actually receives “Uplink Data Resource Allocation” fromthe timing at which the mobile terminal was expected to receive “UplinkData Resource Allocation” from the base station becomes short. In thefirst example of the setting, the time is equal to “a”, as shown in FIG.28. In contrast, in the second example of the setting, the time is equalto “b,” as shown in FIG. 31.

(2) Because the mobile terminal does not have to judge whether thecurrent time exceeds the time limit by which the mobile terminal has toreceive “Uplink Data Resource Allocation” from the base station (ST2907in FIG. 29) in its internal processing, the processing carried out bythe mobile terminal can be simplified.

Each of the first and second examples of the setting of a schedulingrequest signal SR which are explained above can also be used in any oneof Embodiment 1, Embodiment 6, Embodiment 7, Embodiment 8, Embodiment 9,and Embodiment 10.

Furthermore, in a case in which the mobile terminal does not have totransmit an Ack/Nack and/or a CQI, but has to transmit only a schedulingrequest signal, the mobile terminal does not transmit any informationabout the Ack/Nack and the CQI by using the Ack/Nack exclusive channel,but can transmit only the scheduling request by using the Ack/Nackexclusive channel.

An Ack/Nack symbol and CQI symbols are mapped to long blocks (LB2 toLB6) other than the leading LB (LB1), to which an uplink schedulingrequest signal SR is mapped, during a transmission time interval (TTI).In this mapping, the Ack/Nack symbol and CQI symbols at higher-orderdigits with a higher priority among all the CQI symbols are given ahigher priority so that they are repeatedly mapped. In FIG. 14, during 1TTI (=2 subframes), the Ack/Nack symbol is repeatedly mapped threetimes, and CQI1 and CQI2 with a higher priority are repeatedly mappedtwice.

As previously explained, in a case in which the transmission time of anuplink scheduling request signal SR is sufficiently small as shown inthe sequence of FIG. 8, the uplink scheduling request signal SR, andAck/Nack information symbols (an Ack/Nack and/or a CQI), is mapped tothe Ack/Nack exclusive channel. As a result, even when a plurality of“data-non-associated L1/L2 control signals” which have to be transmittedoccur simultaneously in a mobile terminal, while the communicationquality of these important control signals is attained, increase in theradio resources load on the communication system can be prevented, andtransmission with a single carrier method which guarantees a low PAPRand high communication quality can be implemented.

Furthermore, because the Ack/Nack exclusive channel is not a channel(contention based channel), such as an S-RACH, which allowscommunications competition among a plurality of mobile terminals,compared with the case of using an S-RACH, the use of this method canalso provide an advantage of eliminating the necessity to transmit theidentification number (UE-ID) of the mobile terminal throughtransmission of an uplink scheduling request signal SR.

Therefore, in a case in which the frequency of the transmission of an SRis high, it can be said that it is an effective means because therequired number of bits for transmitting an SR is small. In addition, aplurality of time-frequency regions (A and B in FIG. 24) having narrowbands which are separated as shown in FIG. 24 are allocated to theAck/Nack exclusive channel. As a result, a scheduling request signal SRwhich is transmitted by using the Ack/Nack exclusive channel has highresistance to the frequency selective fading. In other words, ascheduling request signal SR can have a frequency diversity gain.

Furthermore, in a case in which a scheduling request signal SR istransmitted from the mobile terminal to the base station by not using anS-RACH, but using the Ack/Nack exclusive channel when the mobileterminal is not performing any transmission of uplink data, but isreceiving downlink data, the radio resources (the frequency-timeregions) which are beforehand allocated for the S-RACH can be releasedfor a UL-SCH or the like, and the method is effective from the viewpointof effective use of the radio resources.

The Ack/Nack exclusive channel is a channel which the mobile terminalhas been using in the state in which the mobile terminal is notperforming any transmission of uplink data, but is receiving downlinkdata. Therefore, by mapping an Ack/Nack and a CQI with an uplinkscheduling request signal SR, to the Ack/Nack exclusive channel, thereis provided an advantage of being able to use the radio resourcescurrently being used effectively, in addition to an advantage of beingable to implement transmission by using a single carrier method whichguarantees both a low PAPR and high communication quality.

Furthermore, as mentioned above, by using a scheduled channel like theAck/Nack exclusive channel, there can be provided a further advantage ofeliminating the necessity to transmit the identification number (UE-ID)of the mobile terminal through transmission of an uplink schedulingrequest signal SR. Therefore, the processing load on the base stationwhen receiving an uplink scheduling request signal can be reduced.

In addition, because the Ack/Nack exclusive channel is used with afrequency band narrower than usually being allocated thereto, theAck/Nack exclusive channel has a small amount of information to beprocessed per a unit time. Therefore, because the processing time ineach of the transmission and the reception also becomes short, theprocess delay (Latency) of the sequence (ST701 to ST703 of FIG. 7 andST801 to ST804 of FIG. 8) including from the transmission of an uplinkscheduling request signal SR up to a start of the transmission becomesshort, and this can contribute to greater efficiency and a speedup ofthe processing of the whole communication system.

On the other hand, there can be considered a mobile communication systemin which even when a mobile terminal is not receiving any downlink data,an Ack/Nack exclusive channel is allocated to the mobile terminal. Morespecifically, there can be considered a case in which, in order toprepare for future downlink scheduling even when there exist no downlinkdata, or maintain synchronization between a base station and a mobileterminal, the mobile terminal notifies the result (CQI) of measurementof the quality of a downlink communication path. Also in such a case,there may be a case in which transmission of a CQI using an Ack/Nackexclusive channel and that of an uplink scheduling request signal SRoccur simultaneously. In such a mobile communication system, in thejudgment of ST602, the mobile terminal had better to makes the judgmentby judging whether the mobile terminal has received allocation of anAck/Nack exclusive channel. In addition, even a mobile communicationsystem in which when a mobile terminal is not receiving any downlinkdata no Ack/Nack exclusive channel is allocated to the mobile terminalcan use this judgment.

In this Embodiment 3, an Ack/Nack exclusive channel to which a pluralityof time-frequency regions having narrow bands which are separated asshown in FIG. 24 are allocated monopolistically is explained. However,this Embodiment 3 can also be adapted to an Ack/Nack exclusive channelnot having a narrow band, as shown in FIG. 23.

Embodiment 4

In a case in which a mobile terminal is not transmitting any uplink data(Uplink data, UL data) such as user data, but is receiving downlink data(Downlink data, DL data) transmitted from a base station, the mobileterminal has to transmit an Ack/Nack signal, which is the result of thereception of the downlink data, and a CQI indicating the quality of adownlink communication path to the base station.

Furthermore, when a necessity for transmission of uplink data occurs ina mobile terminal, the mobile terminal has to transmit an uplinkscheduling request signal SR to the base station.

Hereafter, a method of making a mobile terminal which has to transmit anAck/Nack and an uplink scheduling request signal SR simultaneouslyperform these transmissions simultaneously without increasing the PAPRwill be explained.

In accordance with above-mentioned Embodiment 3, by transmitting anAck/Nack and a CQI with a scheduling request signal SR, by using anAck/Nack exclusive channel, transmission through use of a single carriermethod which guarantees both a low PAPR and high communication qualitycan be implemented. However, in a case of an example shown in FIG. 14,in the transmission, it is necessary to map a symbol indicating thepresence or absence of a scheduling request signal SR to the Ack/Nackexclusive channel. Therefore, in the case of using above-mentionedEmbodiment 3 to multiplex an Ack/Nack, a CQI and an uplink schedulingrequest signal SR (SR) to the Ack/Nack exclusive channel by using a TDMmethod, the following two problems newly arise.

The first problem will be explained hereafter.

Even in a case in which an SR does not have to be transmitted, an LB towhich an SR is mapped has to be allocated in advance. Therefore, a radioresource must always be allocated to the information which does not haveto be transmitted. The problem is therefore that there cannot beprovided an advantage of making effective use of the radio resources.

The second problem will be explained hereafter.

Compared with a case in which an SR is not multiplexed to an Ack/Nackexclusive channel by using a TDM method, there is a disadvantage ofreducing the number of repetitions that an Ack/Nack or a CQI istransmitted. In most cases, an encoding process with high errorcorrection capability is not performed on an Ack/Nack and a CQI, unlikein the case of data. Therefore, in order to prevent a receiving errorfrom occurring in a base station, repeating the same information toincrease the receive power of the base station is important to improvethe reception quality (repetition). The problem is therefore that fromthe viewpoint of maintaining the reception quality of the base station,reduction in the number of LBs which can be used for the repetition hasto be avoided as much as possible.

A method of solving the first and second problems arising newly will beexplained hereafter.

FIG. 15 is a flow chart for explaining processing carried out by amobile terminal which transmits an uplink scheduling request signal, andprocessing carried out by a base station which receives the uplinkscheduling request signal. FIG. 15 shows processing in a case in whichthe mobile terminal is not performing transmission of uplink data, butis receiving downlink data.

The mobile terminal, in ST1500, judges whether a request fortransmission of uplink data has occurred. When no request fortransmission of uplink data has occurred (if No in ST1500), the mobileterminal advances to ST1501. The mobile terminal, in ST1501, maps eitheror both of an Ack/Nack and a CQI to an Ack/Nack exclusive channel.

As an example of the mapping, the example shown in FIG. 9 can be used.The mobile terminal, in ST1503, multiplies the Ack/Nack exclusivechannel by a code (code a) indicating that either or both of theAck/Nack and CQI are mapped to the Ack/Nack exclusive channel.

This multiplication by code is carried out by the modulating unit 10 orthe encoder unit 9. After the multiplication by code is carried out, aprocess of ST1505 is carried out.

In contrast, when, in ST1500, a request for transmission of uplink datahas occurred, a process of ST1502 is carried out. The mobile terminal,in ST1502, maps either or both of the Ack/Nack and the CQI to theAck/Nack exclusive channel, and also maps an uplink scheduling requestsignal SR to the Ack/Nack exclusive channel.

As an example of the mapping, the example shown in FIG. 14 can be used.The mobile terminal, in ST1504, multiplies the Ack/Nack exclusivechannel by a code (code b) indicating that either or both of theAck/Nack and the CQI, and the uplink scheduling request signal SR aremapped to the Ack/Nack exclusive channel, the code being different fromthe code a. This multiplication by code is carried out by the modulatingunit 10 or the encoder unit 9. After the multiplication by code iscarried out, the process of ST1505 is carried out. As the codes a and b,codes which are perpendicular to each other can be used in order toreduce occurrence of an error in the judgment by the base station.

In the mobile communication system, in a case in which code divisionmultiplexing is used as multiplexing of signals from a plurality ofmobile terminals in the Ack/Nack exclusive channel, the Ack/Nackexclusive channel is, in ST1505, multiplied by a code (a code A) foridentifying the plurality of mobile terminals. This multiplication bycode is carried out by the modulating unit 10. After the multiplicationby code is carried out, ST1506 is carried out.

Since the Ack/Nack exclusive channel is, in ST1505, multiplied by thecode (the code A) for identifying the plurality of mobile terminals, thecodes (the codes a and b) by which the Ack/Nack exclusive channel ismultiplied in steps ST1503 and ST1504 can be used in common by theplurality of mobile terminals whose signals are multiplexed into theAck/Nack exclusive channel. The order in which the Ack/Nack exclusivechannel is multiplied by the codes a and A, and the order in which theAck/Nack exclusive channel is multiplied by the codes b and A can bereverse. The mobile terminal, in ST1506, transmits the Ack/Nackexclusive channel to the base station.

The base station, in ST1507, receives the signal transmitted thereto byusing the Ack/Nack exclusive channel. The base station then performs aprocess of multiplying the signal by the codes which are used for themultiplexing of the signals from the plurality of mobile terminals inthe Ack/Nack exclusive channel in order to demultiplex the signaltransmitted thereto by using the Ack/Nack exclusive channel into thesignals from the plurality of mobile terminals.

The base station, in ST1508, performs a correlation operation by usingthe code (code A) indicating the mobile terminal. When the result of thecorrelation operation is equal to or larger than a predeterminedthreshold (if Yes in ST1508), the base station judges that the receptionis the one of the Ack/Nack exclusive channel from the mobile terminal,and carries out a process of ST1509.

When the result of the correlation operation which the base stationperformed in step ST1508 is smaller than the predetermined threshold (ifNo in ST1508), the base station judges that the reception is not the oneof Ack/Nack exclusive channel from the mobile terminal, and ends theprocessing. The correlation operation using the code A is carried out bythe demodulating unit 24. The base station, in ST1509, performs acorrelation operation by using the code a in order to judge whether ornot only the Ack/Nack and the CQI are mapped to the Ack/Nack exclusivechannel from the mobile terminal. When the result of the correlationoperation is equal to or larger than the predetermined threshold (if Yesin ST1509), the base station judges that only the Ack/Nack and the CQIare mapped to the Ack/Nack exclusive channel from the mobile terminal(judges that any scheduling request signal SR is not mapped to theAck/Nack exclusive channel), and carries out a process of ST1510.

The correlation operation using the code a is carried out by thedemodulating unit 24 or the decoder unit 25. The base station, inST1510, carries out the process by judging that only the Ack/Nack andthe CQI are mapped to the received Ack/Nack exclusive channel from themobile terminal.

In contrast, when the result of the correlation operation which the basestation, in ST1509, performed by using the code a is less than thepredetermined threshold (if No in ST1509), the base station carries outST1511. The base station, in ST1511, performs a correlation operation byusing the code b in order to judge whether or not the scheduling requestsignal SR, in addition to the Ack/Nack and the CQI, is mapped to theAck/Nack exclusive channel from the mobile terminal. When the result ofthe correlation operation is equal to or larger than a predeterminedthreshold (if Yes in ST1511), the base station judges that thescheduling request signal SR, in addition to the Ack/Nack and the CQI,is mapped to the Ack/Nack exclusive channel from the mobile terminal,the base station carries out a process of ST1512.

The correlation operation using the code b is carried out by thedemodulating unit 24 or the decoder unit 25. The base station, inST1512, carries out the processing by judging that the schedulingrequest signal SR, in addition to the Ack/Nack and the CQI, is mapped tothe received Ack/Nack exclusive channel from the mobile terminal. Incontrast, when the result of the correlation operation which the basestation, in ST1511, performed by using the code b is less than thepredetermined threshold (if No in ST1511), the base station judges thata receiving error has occurred and ends the processing.

As mentioned above, in FIG. 15, ST1503 in which the multiplication bythe code a is performed, ST1504 in which the multiplication by the codeb is performed, and ST1505 in which the multiplication by the code A isperformed are carried out by the encoder unit 9 and the modulating unit10 in the mobile terminal. A detailed block diagram showing themultiplication by the code a, the multiplication by the code b, and themultiplication by the code A is shown in FIG. 34.

A symbol pattern 3401 for the Ack/Nack exclusive channel in thetransmission buffer 8 or the encoder unit 9 is multiplied by either thecode a 3402 indicating that either or both of the Ack/Nack and the CQIare mapped to the Ack/Nack exclusive channel, or the code b 3403indicating that either or both of the Ack/Nack and the CQI and thescheduling request signal SR are mapped to the Ack/Nack exclusivechannel.

The multiplication by the code a 3402 and the multiplication by the codeb 3403 are switched by a switch 3404. The switching condition of theswitch 3404 is as shown in FIG. 34.

When a request for transmission of uplink data has occurred, i.e., whenthere is an uplink scheduling request, the switch operates in such a waythat the symbol pattern 3401 for the Ack/Nack exclusive channel ismultiplied by the code b. In contrast, when no request for transmissionof uplink data has occurred, i.e., when there is no uplink schedulingrequest, the switch operates in such a way that the symbol pattern 3401for the Ack/Nack exclusive channel is multiplied by the code a.

After multiplying the symbol pattern by the code a or b, the mobileterminal multiplies the symbol pattern by the code A 3405 foridentifying the mobile terminal. After that, a modulation process isperformed on the symbol pattern by the modulating unit 10.

As previously explained, because the mobile terminal multiplies theAck/Nack exclusive channel by a code which differs according to whetheror not a scheduling request signal SR, in addition to an Ack/Nack and aCQI, is mapped to the Ack/Nack exclusive channel, the mobile terminaldoes not have to reserve a symbol for the scheduling request signal SRin the Ack/Nack exclusive channel. For example, the scheduling requestsignal SR is mapped to the first long block LB1 shown in FIG. 14,though, when no scheduling request signal SR is transmitted, theAck/Nack, the CQI, and so on can be mapped to the LB1. Furthermore,because the base station can identify easily whether a signal from acertain mobile terminal includes a scheduling request signal SR by usingthe code by which the signal is multiplied, the base station can performan appropriate process on the signal according to whether or not thescheduling request signal SR is mapped.

In accordance with the W-CDMA method which is a conventional technology,in order to enable a base station to demultiplex a received signal intosignals associated with a plurality of channels transmittedsimultaneously from a mobile terminal, a signal associated with eachchannel is multiplied by a different code (a channelization code) andthe signals associated with the plurality of channels are simultaneouslytransmitted from the mobile terminal to the base station.

In contrast, in accordance with this Embodiment 4, in order todemultiplex the received signal into the several types of information:“Ack/Nack and CQI” or “Ack/Nack, CQI, and SR”), which are transmittedwith the codes, the codes are used.

In this Embodiment 4, either “Ack/Nack and CQI” or “Ack/Nack, CQI, andSR” are transmitted from the mobile terminal to the base station, andboth “Ack/Nack and CQI” and “Ack/Nack, CQI, and SR” which aredemultiplexed with the codes are not transmitted simultaneously. In theabove-mentioned point, this Embodiment 4 differs from the conventionaltechnology (W-CDMA) which uses codes in order to demultiplex a receivedsignal into a plurality of channels transmitted simultaneously.

By using this Embodiment 4, the following advantages can be provided,like in the case of using above-mentioned Embodiment 3.

There can be provided an advantage of enabling a mobile terminal whichhas to transmit, an uplink scheduling request signal SR and an Ack/Nackin a case in which the mobile terminal is not performing anytransmission of uplink data, but is receiving downlink data tosimultaneously transmit them without increasing the PAPR of the mobileterminal.

There can be provided another advantage of eliminating the necessity toadd a UE-ID to an uplink scheduling request signal SR throughtransmission of the uplink scheduling request signal SR by using anAck/Nack exclusive channel. Therefore, in a case in which the frequencyof the transmission of an SR is high, it can be said that it is aneffective means because the required number of bits for transmitting anSR is small. In addition, a plurality of time-frequency regions (A and Bin FIG. 24) having narrow bands which are separated as shown in FIG. 24are allocated to the Ack/Nack exclusive channel. As a result, ascheduling request signal SR which is transmitted by using the Ack/Nackexclusive channel has high resistance to the frequency selective fading.

In other words, a scheduling request signal SR can have a frequencydiversity gain. Furthermore, in a case in which a scheduling requestsignal SR is transmitted from a mobile terminal to a base station by notusing an S-RACH, but using an Ack/Nack exclusive channel when the mobileterminal is not performing any transmission of uplink data, but isreceiving downlink data, the radio resources (the frequency-timeregions) which are beforehand allocated for the S-RACH can be releasedfor a UL-SCH or the like, and the method is effective from the viewpointof effective use of the radio resources.

By using this Embodiment 4, the following advantages can be provided inaddition to the advantages offered in the case of using above-mentionedEmbodiment 3.

In a case in which no SR has occurred in a mobile terminal, an LB whichis beforehand allocated for transmitting an SR in an Ack/Nack exclusivechannel can be eliminated, and therefore the radio resources can be usedmore effectively. Furthermore, because the allocation for mapping an SRcan be eliminated, in the case in which no SR has occurred in the mobileterminal, it becomes unnecessary to reduce the number of repetitions ofan Ack/Nack or a CQI in the conventional Ack/Nack exclusive channel.Therefore, there can be provided an advantage of improving the qualityof reception of the Ack/Nack or the CQI by a base station.

There can be considered a case in which in the mobile communicationsystem, even when a mobile terminal is not receiving any downlink data,an Ack/Nack exclusive channel is allocated to the mobile terminal. Morespecifically, there can be considered a case in which, in order toprepare for future downlink scheduling even when there exist no downlinkdata, or maintain synchronization between a base station and a mobileterminal, the mobile terminal notifies the result (CQI) of measurementof the quality of a downlink communication path. Also in such a case,there may be a case in which transmission of a CQI using an Ack/Nackexclusive channel and that of an uplink scheduling request signal SRoccur simultaneously. This Embodiment 4 can also be used for such amobile communication system.

Hereafter, variants will be explained.

As a first variant, there can be considered a case in which in order tojudge whether only an Ack/Nack and a CQI are mapped to an Ack/Nackexclusive channel, only one of the code a or the code b indicating thatan uplink scheduling request signal SR is furthermore mapped to theAck/Nack exclusive channel is used.

As a concrete example, the mobile terminal multiplies the Ack/Nackexclusive channel by the code a when only an Ack/Nack and a CQI aremapped to the Ack/Nack exclusive channel, whereas when an uplinkscheduling request signal SR, in addition to an Ack/Nack and a CQI, ismapped to the Ack/Nack exclusive channel, the mobile terminal carriesout the process of ST1505 without multiplying the Ack/Nack exclusivechannel by the code b (ST1504 is omitted).

The base station, in ST1509, performs a correlation operation by usingthe code a. When the result of the correlation operation is equal to orlarger than a predetermined threshold, the base station judges that onlyan Ack/Nack and a CQI are mapped to the Ack/Nack exclusive channel andadvances to ST1510.

In contrast, when the result of the correlation operation which the basestation, in ST1509, performed is smaller than the predeterminedthreshold, the base station judges that a scheduling request signal SR,in addition to an Ack/Nack and a CQI, is mapped to the Ack/Nackexclusive channel and then carries out ST1512.

By using this first variant, the number of the codes can be reduced, andthe process of multiplying the Ack/Nack exclusive channel by the codesin the mobile terminal, and the process of performing correlationoperations using the codes in the base station can be reduced.Furthermore, because the number of the codes is reduced, there isprovided an advantage of increasing the number of mobile terminals whichcan be allocated to the Ack/Nack exclusive channel.

As a second variant, there can be considered a case in which for eachmobile terminal whose signals are multiplexed into the Ack/Nackexclusive channel, two codes (a code A and a code B) indicating thatonly an Ack/Nack and a CQI is mapped to the Ack/Nack exclusive channelor an uplink scheduling request signal SR, in addition to the Ack/Nackand the CQI, is mapped to the Ack/Nack exclusive channel are allocated.

As a concrete example, the mobile terminal multiplies the Ack/Nackexclusive channel by the code A when only an Ack/Nack and a CQI aremapped to the Ack/Nack exclusive channel (ST1503), whereas when anuplink scheduling request signal SR, in addition to the Ack/Nack and theCQI, are mapped to the Ack/Nack exclusive channel, the mobile terminalmultiplies the Ack/Nack exclusive channel by the code B (ST1504) andadvances to ST1506. That is, because the codes allocated for each mobileterminal are used, the mobile terminal, in ST1505, does not have tofurther multiply the Ack/Nack exclusive channel by a code indicating themobile terminal.

The base station, in ST1508, performs a correlation operation by usingthe code (the code A) indicating the mobile terminal. When the result ofthe correlation operation is equal to or larger than a predeterminedthreshold, the base station judges that only an Ack/Nack and a CQI aremapped to the Ack/Nack exclusive channel from the mobile terminal, andthen advances to ST1510.

In contrast, when the result of the correlation operation is smallerthan the predetermined threshold, the base station further, in ST1508,performs a correlation operation by using the code (the code B)indicating the mobile terminal. When the result of the correlationoperation is equal to or larger than a predetermined threshold, the basestation judges that an uplink scheduling request signal SR, in additionto the Ack/Nack and the CQI, are mapped to the Ack/Nack exclusivechannel, and then advances to ST1512. That is, the steps ST1509 andST1511 among the steps of FIG. 15 can be omitted.

Furthermore, in this Embodiment 4, the entire Ack/Nack exclusive channelis multiplied by either of the code a indicating that only an Ack/Nackand a CQI are mapped to the Ack/Nack exclusive channel and the code bindicating that an uplink scheduling request signal SR, in addition tothe Ack/Nack and the CQI, is mapped to the Ack/Nack exclusive channel.

In a third variant, a long block on the Ack/Nack exclusive channel towhich an Ack/Nack and a CQI are mapped is multiplied by the code aindicating that effect and a long block on the Ack/Nack exclusivechannel to which an uplink scheduling request signal SR is mapped ismultiplied by the code b indicating that effect.

Concretely, the steps ST1503 and ST1504 among the steps shown in FIG. 15are omitted, and, instead, a step of multiplying a long block on theAck/Nack exclusive channel to which an Ack/Nack and a CQI are mapped bythe code a indicating that effect, and multiplying a long block on theAck/Nack exclusive channel to which an uplink scheduling request signalSR is mapped by the code b indicating that effect is added.

Furthermore, the steps of ST1509, ST1510, ST1511, and ST1512 among thesteps carried out by the base station are omitted, and, instead, aprocess of performing a correlation operation by using the code a inorder to judge whether or not a long block is the one to which anAck/Nack and a CQI are mapped is added.

When the result of the correlation operation is equal to or larger thana predetermined threshold, the base station judges that the long blockis the one to which an Ack/Nack and a CQI are mapped, and then performsa subsequent process. In contrast, when the result of the correlationoperation is smaller than the threshold, the base station performs acorrelation operation by using the code b in order to judge whether ornot the long block is the one to which an uplink scheduling requestsignal SR is mapped.

When the result of the correlation operation is equal to or larger thana predetermined threshold, the base station judges that the long blockis the one to which an uplink scheduling request signal SR is mapped,and then performs a subsequent process. In this case, in addition to theadvantages provided by Embodiment 4, there can be provided an advantageof being able to freely choose the location of a long block on theAck/Nack exclusive channel to which an uplink scheduling request signalSR is mapped.

Hereafter, a fourth variant will be explained.

One type of mapping to the Ack/Nack exclusive channel is providedregardless of whether or not an SR is included in the mapping. Themapping can use the example of FIG. 9. Therefore, information which is,in ST1501 and ST1502, actually mapped to the Ack/Nack exclusive channelis only an Ack/Nack or/and a CQI.

Because subsequent processing carried out by the mobile terminal is thesame as that of FIG. 15, the explanation of the subsequent processingwill be omitted hereafter.

The base station which has received the Ack/Nack exclusive channel, inST1510, judges that the base station has not received an SR from themobile terminal, and then performs a process on the Ack/Nack exclusivechannel after judging that only an Ack/Nack or/and a CQI are mapped tothe Ack/Nack exclusive channel.

The base station, in ST1512, judges that the base station has receivedan SR from the mobile terminal, and then performs the processing on theAck/Nack exclusive channel by judging that only an Ack/Nack or/and a CQIare mapped to the Ack/Nack exclusive channel.

FIG. 27 is an explanatory drawing for explaining an example of themapping of information to the Ack/Nack exclusive channel according tothe fourth variant of Embodiment 4. In accordance with the fourthvariant of this Embodiment 4, it becomes unnecessary to map an SR to theAck/Nack exclusive channel, and it becomes possible to make furthereffective use of the radio resources. Furthermore, even in a case inwhich an uplink scheduling request signal SR is transmitted from themobile terminal, the number of repetitions of an Ack/Nack or/and a CQIcan be maintained. Therefore, there can be provided an advantage ofbeing able to maintain the quality of reception of an Ack/Nack or/and aCQI by the base station even in a case in which an uplink schedulingrequest signal SR is transmitted to the base station, like in a case inwhich no SR is transmitted to the base station. That is, the use of thismethod can offer an advantage of, when desiring to transmit an uplinkscheduling request signal SR, being able to not only use physicalchannels and radio resources which have already been used, but alsohardly affect the amount of information and the quality of other datawhich are being transmitted by using the radio resources. Therefore,when, for example, allocating an uplink Ack/Nack exclusive channel to aradio resource, the base station does not have to take intoconsideration the influence of transmission of an uplink schedulingrequest signal SR upon selection of a condition of the radio resource (afrequency bandwidth or the like).

In this Embodiment 4 and its variants, the case in which themultiplexing of a plurality of mobile terminals into an Ack/Nackexclusive channel is carried out by using a CDM method is explained. Asan alternative, Embodiment 4 and the variants can also be applied to acase in which an FDM method or a TDM method is used as the multiplexingmethod. In this Embodiment 4 and its variants, an Ack/Nack exclusivechannel to which a plurality of time-frequency regions having narrowbands separated as shown in FIG. 24 are allocated monopolistically isexplained. However, this Embodiment 4 and its variants can also beapplied to an Ack/Nack exclusive channel not having a narrow band, asshown in FIG. 23.

Embodiment 5

FIG. 16 is a flow chart for explaining processing carried out by amobile terminal which transmits an uplink scheduling request signal, andprocessing carried out by a base station which receives the uplinkscheduling request signal.

The mobile terminal, in ST1601, judges whether or not the mobileterminal is transmitting uplink data. When the mobile terminal istransmitting uplink data, the mobile terminal advances to ST1602. Themobile terminal which is transmitting uplink data, i.e., which isscheduled to have an uplink resource from the base station does not haveto transmit an uplink scheduling request signal SR, and therefore, whenthe mobile terminal is, in ST1601, transmitting uplink data, the mobileterminal can carry out a process of advancing to ST1602 without goingvia judgment of ST1604. In other words, it can be considered that in onemobile terminal, uplink data and an uplink scheduling request signal SRdo not coexist in a UL-SCH, and the relation of SC-FDMA is not satisfiedand hence no increase is produced in the PAPR in the mobile terminal.

The mobile terminal, in ST1602, multiplies the UL-SCH by a code (a codec) indicating that a symbol mapped to the UL-SCH is uplink data. Thismultiplication by code is carried out by the modulating unit 10 or theencoder unit 9. After performing the multiplication by the code c, themobile terminal advances to ST1603.

The mobile terminal, in ST1603, maps the uplink data to a resourceincluded in the UL-SCH on which scheduling has been performed by thebase station, and advances to ST1607. In contrast, when, in ST1601, themobile terminal is not transmitting any uplink data, the mobile terminaladvances to ST1604.

The mobile terminal, in ST1604, judges whether a request fortransmission of uplink data has occurred. When no request fortransmission of uplink data has occurred, the mobile terminal returns toST1601. In contrast, when a request for transmission of uplink data hasoccurred, the mobile terminal advances to ST1605.

The mobile terminal, in ST1605, multiplies the UL-SCH by a code (a coded) indicating that the symbol mapped to the UL-SCH is an uplinkscheduling request signal SR. This multiplication by code is carried outby the modulating unit 10 or the encoder unit 9. After performing themultiplication by the code d, the mobile terminal advances to ST1613.The mobile terminal, in ST1613, multiplies the UL-SCH by a code (a codeA) for identifying the mobile terminal. This multiplication by code iscarried out by the modulating unit 10. After performing themultiplication by the code, the mobile terminal carries out ST1606. Themobile terminal, in ST1606, maps an uplink scheduling request signal SR(a resource request, a preamble, a message, and so on) to a resourceincluded in the UL-SCH, and advances to ST1607. The order in which theprocesses of ST1613 and ST1606 are carried out can be reverse. As thecodes c and d, codes which are perpendicular to each other can be usedin order to reduce occurrence of errors in the judgment by the basestation.

The mobile terminal, in ST1607, transmits the UL-SCH to the basestation. The base station, in ST1608, receives the UL-SCH transmittedthereto from the mobile terminal. The base station, in ST1609, performsa correlation operation by using the code c in order to judge whether ornot uplink data are mapped to the UL-SCH.

When the result of the correlation operation is equal to or larger thana predetermined threshold, the base station judges that uplink data aremapped to the UL-SCH, and then advances to ST1610. The correlationoperation using the code c is implemented by the demodulating unit orthe decoder unit. The base station, in ST1610, carries out theprocessing by judging that uplink data are mapped to the UL-SCH.

Because the mobile terminal transmits the uplink data by using apredetermined radio resource for the UL-SCH which the base station hasallocated and notified, the base station can distinguish the receptionof the UL-SCH channel from the mobile terminal from those from othermobile terminals. In contrast, when, in ST1609, the result of thecorrelation operation which the base station has carried out by usingthe code c is smaller than the predetermined threshold, the base stationadvances to ST1614.

The base station, in ST1614, performs a correlation operation by usingthe code (the code A) which is used for multiplexing of signals frommobile terminals into the UL-SCH. When the result of the correlationoperation is equal to or larger than a predetermined threshold (if Yesin ST1614), the base station judges that the base station has receivedthe UL-SCH from the mobile terminal, and then carries out a process ofST1611. In contrast, when the result of the correlation operation whichthe base station, in ST1614, carried out is smaller than thepredetermined threshold (if No in ST1614), the base station judges thatthe base station has not received the UL-SCH from the mobile terminal,and ends the processing. The correlation operation using the code A iscarried out by the demodulating unit 24.

The base station, in ST1611, performs a correlation operation by usingthe code d in order to judge whether or not an uplink scheduling requestsignal SR is mapped to the UL-SCH. When the result of the correlationoperation is equal to or larger than a predetermined threshold, the basestation judges that an uplink scheduling request signal SR is mapped tothe UL-SCH, and then advances to ST1612. The correlation operation usingthe code d is implemented by the demodulating unit 24 or the decoderunit 25. The base station, in ST1612, carries out the processing byjudging that an uplink scheduling request signal SR is mapped to theUL-SCH.

As previously explained, because the base station can judge whether ornot uplink data are mapped to the UL-SCH and whether or not an uplinkscheduling request signal SR is mapped to the UL-SCH by using the codesc and d, there is provided an advantage of eliminating the necessity toreserve radio resources for the RACH (Non-S-RACH and S-RACH)transmission (FIG. 17). Therefore, there is provided an advantage ofbeing able to use the uplink radio resources efficiently. Furthermore,when a request for transmission of an uplink scheduling request signalSR occurs in a mobile terminal, the use of a conventional method doesnot make it possible for the mobile terminal to transmit the SR to thebase station until an uplink resource timing reserved for the RACH(Non-S-RACH and S-RACH). In contrast, according to the presentinvention, the mobile terminal can transmit an uplink scheduling requestsignal SR to the base station at all times.

Therefore, there is provided an advantage of being able to reduce thecontrol delay in the mobile communication system. Furthermore, becausein a case in which a mobile terminal maps an uplink scheduling requestsignal to a UL-SCH, multiplexing is carried out by using a code (a codeA) for identification of the mobile terminal, also when schedulingrequest signals SRs are simultaneously transmitted to the base stationfrom a plurality of mobile terminals, the base station can receive thescheduling request signals from those terminals while discriminatingthem from one another. Therefore, collision among the scheduling requestsignals from the plurality of mobile terminals which can happen in thecase of using an S-RACH can be prevented.

In addition, this Embodiment 5 can also be applied to a multiplexingmethod of multiplexing transmission, via an uplink, of an Ack/Nack and aCQI for downlink data and uplink data (a UL-SCH) in a case in which amobile terminal is receiving downlink data without performing anytransmission of uplink data. Because the operation of the mobilecommunication system is the same as the processing shown in the flowchart of FIG. 16, the explanation of the operation will be omitted.

Like in the case of Embodiment 5, it can be considered that in onemobile terminal, transmission of an Ack/Nack and transmission of a CQIdo not coexist in a case in which no uplink data exist in the UL-SCH andthe mobile terminal is not performing any transmission of uplink datavia the UL-SCH, but is receiving downlink data, and the relation ofSC-FDMA is not satisfied and hence no increase is produced in the PAPRin the mobile terminal.

Therefore there is provided an advantage of, in a case in which a mobileterminal is receiving downlink data without performing any transmissionof uplink data, eliminating the necessity to dispose an Ack/Nackexclusive channel (FIGS. 23 and 24) for transmission of an Ack/Nack fordownlink data via an uplink. Furthermore, the radio resources which areallocated for the Ack/Nack exclusive channel can be released for theUL-SCH or the like. Therefore, there can be provided another advantageof being able to use the uplink radio resources efficiently.

Embodiment 6

In a case in which a mobile terminal is not transmitting any uplink data(Uplink data, UL data) such as user data, but is receiving downlink data(Downlink data, DL data) transmitted from a base station, the mobileterminal has to transmit an Ack/Nack, which is the result of thereception of the downlink data, and a CQI signal to the base station.

Furthermore, when a necessity for transmission of uplink data occurs ina mobile terminal, the mobile terminal has to transmit an uplinkscheduling request signal SR to a base station. Hereafter, a method ofmaking a mobile terminal which has to transmit an Ack/Nack and an uplinkscheduling request signal SR simultaneously perform these transmissionssimultaneously without increasing the PAPR in the mobile terminal willbe explained.

The nonpatent reference 1 discloses that in a case in which a mobileterminal is receiving downlink data without performing transmission ofuplink data, an Ack/Nack or/and a CQI are transmitted by suing anAck/Nack exclusive channel having a broad band as shown in FIG. 23.

The nonpatent reference 4 discloses that in the case in which a mobileterminal is receiving downlink data without performing transmission ofuplink data, an SR is transmitted by using an S-RACH.

However, the above-mentioned two nonpatent references 1 and 4 suggestnothing about the problems of the present invention. The problems of thepresent invention will be explained hereafter, though they are alreadymentioned.

There may be a case in which a mobile terminal has to simultaneouslycarry out a process of transmitting an uplink Ack/Nack and a CQI byusing an Ack/Nack exclusive channel and a process of transmitting an SRby using an S-RACH. In this case, because those signals have nocorrelation among them, when transmitted simultaneously, they are nottransmitted with single carrier transmission, but are transmitted withmulti carrier transmission. In the case in which such signals having nocorrelation among them are transmitted simultaneously, the PAPR becomeshigh because the time waveforms of the transmission signals have a highpeak. A problem is that as the PAPR becomes high, the power consumptionof the mobile terminal increases and therefore the cell coverage becomesnarrow. A further problem is that as the PAPR becomes high, thosesignals become an interference wave to other mobile terminals and thecommunication system.

In a case in which a mobile terminal has to transmit an uplink Ack/Nack,a CQI, and an SR simultaneously, the mobile terminal should use singlecarrier transmission in order to reduce the increase in the PAPR in themobile terminal.

There can be considered a case in which, when a mobile terminal uses anAck/Nack or/and a CQI which are transmitted by using an Ack/Nackexclusive channel having a broad band, which is disclosed by theconventional technology, and an SR which is transmitted by using anS-RACH, just as they are, a necessity for the mobile terminal totransmit those pieces of information simultaneously occurs.

Therefore, this Embodiment 6 presents multiplexing of an Ack/Nack or/anda CQI, and an SR into either one of an Ack/Nack exclusive channel towhich one certain time-frequency region is allocated monopolistically,and an S-RACH.

The multiplexing method will be explained hereafter. A method oftransmitting an uplink scheduling request signal SR, an Ack/Nack, and aCQI together by using either an Ack/Nack exclusive channel to which onecertain time-frequency region as shown in FIG. 23 is allocatedmonopolistically, or an S-RACH as shown in FIG. 25 will be explained.

Because a region in units of a subframe with respect to time and inunits of one or more resource units with respect to frequency isallocated to each of the Ack/Nack exclusive channel and the S-RACH, thepresent invention can be applied to each of the channels.

In this Embodiment 6, a case in which when a necessity to simultaneouslytransmit an Ack/Nack or/and a CQI, and an uplink scheduling requestsignal SR occurs in a mobile terminal, the mobile terminal transmits theAck/Nack and/or the CQI, with the uplink scheduling request signal SRtogether by using an S-RACH will be shown. In other words, it means thateven a mobile terminal which receives downlink data and therefore has totransmit an Ack/Nack or/and a CQI does not use an Ack/Nack exclusivechannel during a time interval during which the mobile terminal isperforming transmission of an uplink scheduling request signal SR.Furthermore, during the time interval during which the mobile terminalis transmitting an uplink scheduling request signal SR, the mobileterminal can perform transmission of a CQI or transmission of anAck/Nack and a CQI by using an S-RACH, and is therefore allowed not touse an Ack/Nack exclusive channel at that time.

FIG. 18 is a flow chart for explaining processing carried out by amobile terminal, the processing including up to a process oftransmitting an uplink scheduling request signal. Hereafter, theoperation of the mobile terminal will be explained with reference toFIG. 18. In FIG. 18, because each of the same steps as those shown inFIG. 6 denote the same step or a like step, the explanation of the stepswill be omitted hereafter.

Steps ST601 to ST603 are the same as those shown in FIG. 6. When, inST602, is receiving downlink data, the mobile terminal carries outST1801. In ST1801, the mobile terminal, maps an Ack/Nack, and/or a CQIwith an uplink scheduling request signal SR onto an S-RACH, andtransmits them to the base station. Because the processing of the mobilecommunication system is the same as that shown in FIG. 52, theexplanation of the processing will be omitted hereafter.

Next, methods of mapping those pieces of information onto the S-RACHwill be explained hereafter.

According to a first mapping method, a preamble and a message, anAck/Nack, and a CQI are mapped onto the S-RACH. FIG. 19 is anexplanatory drawing showing radio resources in which a preamble and amessage, an Ack/Nack, and a CQI are mapped onto the S-RACH.

According to a second mapping method, a preamble, an Ack/Nack, and a CQIare mapped onto the S-RACH. Message information required for an uplinkscheduling request signal SR is transmitted at the timing of the nextS-RACH transmission or by using the uplink resources which are allocatedto the mobile terminal by the base station.

FIG. 20 is an explanatory drawing showing radio resources in which apreamble and a message, an Ack/Nack, and a CQI are mapped onto theS-RACH.

According to a third mapping method, a preamble and a message are mappedonto the S-RACH as usual. An Ack/Nack and a CQI are newly added into amessage on the S-RACH which is transmitted in a state in which uplinktime synchronization is established. FIG. 21 is an explanatory drawingshowing radio resources in which a preamble and a message, an Ack/Nack,and a CQI are mapped onto the S-RACH.

As previously explained, by mapping both an uplink scheduling requestsignal SR and Ack/Nack information symbols (an Ack/Nack and/or a CQI)not to an Ack/Nack exclusive channel, but to an S-RACH with the uplinkscheduling request signal SR and the Ack/Nack information symbols beingseparated with respect to time, they are not transmitted simultaneouslybecause they are transmitted with them being separated with respect totime. As a result, even when a plurality of “data-non-associated L1/L2control signals” which have to be transmitted occur simultaneously inone mobile terminal, while the communication quality of these importantcontrol signals is attained, increase in the radio resources load on thecommunication system can be prevented, and transmission with a singlecarrier method which guarantees a low PAPR and high communicationquality can be implemented.

Furthermore, compared with the case in which an Ack/Nack and a CQI aretransmitted with a plurality of time-frequency regions having narrowbands which are separate from one another, in the case of using themethod according to this embodiment of transmitting an Ack/Nack and aCQI by using either an Ack/Nack exclusive channel to which one certaintime-frequency region as shown in FIG. 23 is allocated monopolistically,or an S-RACH as shown in FIG. 25, the bandwidth becomes large.Therefore, the amount of information which can be transmitted with theradio resources allocated monopolistically increases.

As a result, there can be provided an advantage of being able to changethe repetition pattern of an Ack/Nack and a CQI (e.g., the number ofrepetitions) according to the environment of the communication path. Bychanging the repetition pattern under an instruction from the basestation according to the environment of the communication path, thequality of reception of an Ack/Nack and a CQI can be maintained constantregardless of the environment of the communication path.

Embodiment 7

In a case in which a mobile terminal is synchronized with a basestation, and is carrying out neither transmission of uplink data (Uplinkdata, UL data) nor reception of downlink data (Downlink data, DL data),there exists no Ack/Nack exclusive channel because the mobile terminaldoes not have to transmit an Ack/Nack to downlink data via an uplink. Amethod of, when an uplink transmission request occurs in such a case,transmitting an uplink scheduling request signal SR by using a signalfor uplink communication quality measurement, which is called “soundingreference signal” (sounding reference signal, Sounding Reference Signal(RS)) without using radio resources for an S-RACH will be disclosed.

The use of this method makes it possible to not only release the radioresources reserved for an S-RACH, but also make effective use of theresources because a radio resource region which is shared with othermobile terminals is used for transmission of a Sounding RS. Furthermore,one sounding reference signal (Sounding RS) can be made to have the twofollowing functions: measurement of the communication quality of achannel via which transmission is started; and the functions of anuplink schedule request signal SR.

A Sounding RS is transmitted from a mobile terminal UE to a base stationeNB in order to enable the base station to measure the communicationquality of the uplink. In the 3GPP, the specifications of two types ofreference signals: a reference signal for demodulation (a DemodurationRS); and a reference signal for uplink channel quality measurement (aSounding RS) are currently under debate as uplink reference signals(Reference signals).

A plurality of suggestions are currently written together in thenonpatent reference 3, and the specifications have not been determinedyet.

In this Embodiment 7, a case in which a sounding reference signal (aSounding RS) is transmitted only during transmission of uplink data willbe considered.

A part of allocation of radio resources for a Sounding RS duringtransmission of uplink data in this Embodiment 7 is shown in FIGS. 35(a) and 35(b).

First, FIG. 35( a) shows an example in which a sounding RS is allocatedto two short blocks (SB) within 2 TTIs with the total bandwidth of onetime-frequency region. A radio resource allocation method in a case inwhich two mobile terminals (UE1 and UE2) use a part of onetime-frequency region is shown in FIG. 35( a).

In the figure, reference numeral 501 denotes a data symbol of the mobileterminal UE1, reference numeral 502 denotes a Sounding RS which themobile terminals UE1 and UE2, and which all mobile terminals using thistime-frequency region use in common, reference numeral 503 denotes areference signal for demodulation (Demoduration) of the mobile terminalUE1, reference numeral 504 denotes a data symbol of the mobile terminalUE2, and reference numeral 505 denotes a reference signal fordemodulation (Demoduration) of the mobile terminal UE2. Among these, twoSBs with the total bandwidth of one time-frequency region is allocatedwithin two 2 TTIs as the region of the Sounding RS 502.

Similarly, an example in which a Sounding RS is allocated to two longblocks (LB) within 2 TTIs with the total bandwidth of one time-frequencyregion is shown in FIG. 35( b). A radio resource allocation method in acase in which three mobile terminals (UE1, UE2, and UE3) use a part ofone time-frequency region is shown in FIG. 35( b). In the figure,reference numeral 506 denotes a data symbol of the mobile terminal UE1,reference numeral 507 denotes a reference signal for demodulation of themobile terminal UE1, reference numeral 508 denotes a data symbol of theUE2, reference numeral 509 denotes a reference signal for demodulationof the mobile terminal UE2, reference numeral 511 denotes a data symbolof the mobile terminal UE3, reference numeral 512 denotes a referencesignal for demodulation of the mobile terminal UE3, and referencenumeral 510 denotes a Sounding RS which the mobile terminals UE1, UE2,and UE3, and all other mobile terminals using this time-frequency regionuse in common.

As mentioned above, two LBs with the total bandwidth of onetime-frequency region is made available for the radio resources for aSounding RS.

In either of the cases of FIGS. 35( a) and 35(b), a Sounding RS iscode-multiplexed for each UE. Because radio resources having a wide bandcan be shared and used for a Sounding RS by a plurality of terminals,the base station can measure the status of the frequency selectivefading and can therefore carry out appropriate uplink scheduling.Furthermore, because a signal of each of the plurality of mobileterminals is code-multiplexed, the base station can carry outhigh-accuracy quality measurement for each of the plurality of mobileterminals.

As a case in which a mobile station is synchronized with a base stationand a transmission request occurs in a state in which no transmission ofuplink data is carried out, there can be considered a case in which themobile terminal receives downlink data, and, in order for the mobileterminal to transmit an Ack/Nack and a CQI to the downlink received datavia the uplink, an ACK/Nack exclusive channel is allocated to the mobileterminal, and a case in which the mobile terminal receives downlinkdata, but no ACK/Nack exclusive channel is allocated to the mobileterminal, as described in Embodiment 3. In a flow chart of FIG. 37, amethod of transmitting an uplink scheduling request signal SR in each ofthe cases is shown.

First, when recognizing occurrence of an uplink data transmissionrequest (ST5201), the mobile terminal checks to see whether or not anAck/Nack exclusive channel via which the mobile terminal transmits anAck/Nack to downlink received data is allocated in the uplink (ST5202).When an Ack/Nack exclusive channel is allocated in the uplink, themobile terminal transmits an uplink scheduling request signal SR, aswell as an Ack/Nack and a CQI, by using the Ack/Nack exclusive channel(ST5204). Processing in this case is the same as that explained inEmbodiment 3. In contrast, when, in ST5202, no Ack/Nack exclusivechannel is allocated in the uplink, the mobile terminal transmits aSounding RS for uplink quality measurement (a Sounding Reference signal)which serves as an uplink scheduling request signal SR to the basestation (ST5203).

There can be considered a case in which in the mobile communicationsystem, even when a mobile terminal is not receiving any downlink data,an Ack/Nack exclusive channel is allocated to the mobile terminal. Morespecifically, there can be considered a case in which, in order toprepare for future downlink scheduling even when there exist no downlinkdata, or maintain synchronization between a base station and a mobileterminal, the mobile terminal notifies the result (CQI) of measurementof the quality of the downlink communication path. In such a case, itcan be considered that the judgment of ST5202 is suitable as mentionedabove.

In contrast, there can be considered a case in which in the mobilecommunication system, only when there exist downlink data destined for amobile terminal, an Ack/Nack exclusive channel is allocated to themobile terminal. In such a case, in the judgment of ST5202, the mobileterminal can judge whether or not the mobile terminal is receivingdownlink data.

A concrete example of a sequence when an uplink transmission requestoccurs under a condition resulting in a “No” in a branch of ST5202 ofFIG. 37, i.e., in a state in which there is no allocation of an ACK/Nackexclusive channel will be explained in FIG. 36.

This embodiment is based on that synchronization is established betweena mobile terminal and a base station. Therefore, synchronization has tobe established between the mobile terminal and the base station by usinga certain method before this embodiment is applied. As an example of themethod, FIG. 36 shows a case in which a non-synchronous random accesssignal (Non-Synchronous Random Access) is transmitted from the mobileterminal to the base station.

The base station eNodeB, in ST5101, receives a synchronous request fromthe mobile terminal UE, specifies the mobile terminal which has made therequest, and also establishes synchronization with this mobile terminaland then recognizes that the mobile terminal has changed to an Activestate. Furthermore, the base station, in next ST5102, notifies themobile terminal that synchronization with this mobile terminal isestablished, and also notifies the mobile station of L1/L2 controlinformation which is required for settings of uplink and downlinkcommunication paths and whose setting value is nearly fixed(semi-static) for the reason of being set to other UEs in common withthe mobile terminal.

When transmitting an uplink scheduling request signal SR by using asounding RS for measurement of the communication quality of the uplink,the base station notifies Sounding-RS-related control information aswell as the notification of the synchronization establishment becausethe base station has to transmit a “Sounding RS which serves as anuplink scheduling request” if there is no transmission of uplink data.Because the Sounding RS for measurement of the communication quality ofthe uplink also uses the radio resources which the mobile terminalshares with the other UEs, the base station eNodeB, in ST5102, notifiesthe mobile terminal UE of mobile terminal identifying information (asequence number or a UE-ID) which is allocated to this mobile terminaland is used for the code division multiplexing, the mobile terminalidentifying information being included in the L1/L2 control informationfor controlling the Sounding RS, the frequency bandwidth (BW) of a radioresource which is scheduled to be allocated to the transmission of theSounding RS, and so on, thereby enabling the transmission of theSounding RS also when any uplink data are not transmitted.

In a case in which the Sounding RS is not used for notification of anuplink scheduling request signal SR, but is transmitted only duringtransmission of uplink data, what is necessary is just not to carry outthe transmission along with the notification of the synchronizationestablishment, but to notify the Sounding RS-related control information(the sequence number, the BW, etc.) at, for example, the time (ST5104)of resource allocation for uplink data, unlike in the above case.Furthermore, the above-mentioned transmission along with thenotification of the synchronization establishment means that they do nothave to be carried out at the same time.

When an uplink transmission data request occurs in the mobile terminal,the mobile terminal UE transmits a Sounding RS according to the sequencenumber of the UE for the uplink Sounding RS, which the mobile terminal,in ST5102, received from the base station, and/or the controlinformation, such as the frequency band which is scheduled to beallocated to the Sounding RS transmission, so as to notify the basestation that the specific mobile terminal UE has an uplink schedulingrequest (ST5103). Such a Sounding RS is called a “Sounding RS whichserves as an uplink scheduling request.”

A Sounding RS of each mobile terminal is multiplexed with a CAZACsequence code which has occurred with the sequence number for the mobileterminal UE which the mobile terminal, in ST5102, received, and istransmitted with the frequency band and at the timing which are notifiedfrom the base station.

By receiving the Sounding RS in the time-frequency region of the radioresources, which this mobile terminal uses, to correlate the reception,the base station can detect the reception of the Sounding RS of themobile terminal. When detecting a Sounding RS from a mobile terminalwhich has not transmitted any uplink data through the receptiondetection, the base station can judge this Sounding RS to be an uplinkscheduling request signal SR (ST5103). This is because this Embodiment 7is based on that only during transmission of uplink data, a Sounding RSis transmitted.

In the above-mentioned example, the use of a CAZAC sequence code for themethod of identifying a mobile terminal in a Sounding RS is shown. As analternative, another method can be used.

When judging that the sounding RS which the base station has receivedfrom the mobile terminal is a scheduling request signal SR, the basestation notifies the control information, such as radio resourceallocation required for transmission of uplink data, by using an “UplinkData Resource Allocation” message (ST5104). The mobile terminal thenstarts transmission of uplink data by using the radio resources receivedfrom the base station (ST5105).

A flow chart in the base station at the time when the base stationeNodeB, in ST5102, notifies the BW is shown in FIG. 39.

First, a flow of instructions at the time when the base station eNodeBnotifies the BW will be explained with reference to FIG. 39.

The base station, in ST5401, checks whether or not synchronization isestablished with the mobile terminal UE, and, when synchronization isnot established, waits until the base station receives a synchronousrequest via a Non-Sync RACH (ST5402). When receiving a synchronousrequest, the base station establishes synchronization with the mobileterminal, as shown in the explanation of ST5102 of FIG. 36 (ST5403), andthen transmits L1/L2 control information for Sounding RS to the mobileterminal UE in semi-static mode (ST5404). The identification information(the sequence number or the UE-ID) of the UE for uplink Sounding RS, andthe BW of uplink Sounding RS are included in this L1/L2 controlinformation.

When judging that synchronization is established as a result of, inST5401, checking synchronization with the UE, the base station, inST5405, checks to see whether or not the mobile terminal is receivingdownlink data. While receiving downlink data, the base station notifiesL1/L2 control information for Sounding RS to the mobile terminal UE indynamic mode, and changes the frequency bandwidth (BW) dynamically(ST5406).

In the flow chart of FIG. 39, the base station notifies the BW of uplinkSounding RS by using both the L1/L2 control information in semi-staticmode and the one in dynamic mode. In practice, the base station cannotify the BW of uplink Sounding RS by using either one of the two typesof L1/L2 control information: the semi-static L1/L2 control informationand the dynamic L1/L2 control information.

As a method of retransmitting an uplink Sounding RS which serves as anuplink scheduling request signal SR in a mobile terminal, in accordancewith this Embodiment 7, there are provided the following two methods: amethod of setting up a timer which times a predetermined time intervalin the mobile terminal, and, when an “Uplink Data Resource Allocation”message cannot be received in ST5104 from the base station by the timethe timer times out, retransmitting an uplink Sounding RS, and a methodof continuing transmitting an uplink Sounding RS continuously until, inST5104, receiving an “Uplink Data Resource Allocation” message. Becausethese methods are already explained in detail with reference to theexplanatory FIGS. 28 to 30 of Embodiment 3, and FIGS. 31 to 33, theexplanation of the methods will be omitted hereafter.

When, in ST5103, transmitting a Sounding RS which serves as an uplinkscheduling request signal SR, the mobile terminal naturally uses an SBor LB which the mobile terminal ought to use for Sounding RS for(usually) measurement of the communication quality of the uplink, andhas to make the frequency band and bandwidth (BW: BandWidth) of the SBor LB be equal to those of a general Sounding RS. This is because sincefor a Sounding RS, a plurality of mobile terminals to which an identicaltime-frequency region is allocated in such a way as to use the identicaltime-frequency region carries out code division multiplexing of the sameSB (or LB) region to use this, if one mobile terminal changes the endsof the frequency band which the mobile terminal uses for Sounding RS incommon with other mobile terminals or uses another block (LB or SB),data and reference signals of other mobile terminals are crushed.Therefore, in a case in which, for example, a Sounding RS formeasurement (usually) of the communication quality of the uplink has abandwidth equal to the entire bandwidth of the base station, a SoundingRS which serves as an uplink scheduling request SR also has the samebandwidth, and, when the base station sets up a plurality of BWs(frequency bands) for a Sounding RS for measurement (usually) of thecommunication quality of the uplink, the mobile terminal uses the sameBW as that of another mobile terminal to which the same time-frequencyregion as that of the mobile terminal itself is allocated as a radioresource.

There can be a case in which the base station eNodeB judges and selectsthe BW for a Sounding RS which serves as an uplink scheduling requestSR, the BW being used for the mobile terminal, and a case in which themobile terminal UE can judge and select the BW by itself.

A flow chart showing a judging method in the case in which the basestation eNodeB selects the BW is shown in FIG. 40, and a flow of ajudging method in the case in which the mobile terminal selects the BWis shown in FIG. 41.

Next, a process flow in the case in which the base station eNodeBselects the BW of an uplink Sounding RS will be explained. Thisselection flow shows a method of determining the BW included in eitherthe semi-static (semi-static) L1/L2 control information which is, inST5404 of the flow chart shown in FIG. 39, notified to the UE, or thedynamic (dynamic) L1/L2 control information which is, in ST5406,notified to the UE.

FIG. 40 shows a process flow in the case in which the base stationeNodeB selects the frequency bandwidth (Band Width: BW) of an uplinkSounding RS.

First, the base station, in ST5501 of the figure, checks to see whetherthere exist two or more BWs with which an uplink Sounding RS istransmitted, and, if there exists only one BW, the base station sets theBW to be equal to the BWs of uplink Sounding RSs of all other mobileterminals UE (ST5502). In contrast, when there exist two or more BWswith which an uplink Sounding RS is transmitted, the base station checkswhether or not the number of UEs each of which transmits a Sounding RSwhich serves as an uplink scheduling request signal SR with the same BWis appropriate (ST5504), checks whether or not one of the two or moreBWs includes frequencies which can be allocated to the UE at the celledge (ST5505), checks whether one of the two or more BWs shows a goodresult of reporting the downlink CQI (the channel quality or thedownlink communication path quality) (ST5506), and then searches throughthe two or more BWs for one BW which satisfies these conditions(ST5507). The base station then determines one BW which satisfies theconditions of ST5504 to ST5506 as the BW for uplink Sounding RS(ST5508).

A process flow in the case in which the UE carries out theabove-mentioned selection of one BW is shown in FIG. 41. The result ofthe selection of one BW for uplink Sounding RS which is carried out bythe UE is reflected, referring to the flow chart of FIG. 39, in the BWnotified by using the dynamic L1/L2 down control information when themobile terminal is, in ST5405, receiving downlink data. First, themobile terminal receives the number of BWs for uplink Sounding RS fromthe base station via a channel such as a BCH (ST5601). The mobileterminal checks to see whether there exist two or more BWs for uplinkSounding RS (ST5602), and, when there exist only one BW, selects thesame BW as the BWs for uplink Sounding RSs of all other UEs (ST5603). Incontrast, when there exist two or more BWs, the mobile terminal selectsone BW from among them in order, and searches for one BW which satisfiesthe conditions “the quality of the downlink CQI is good” of ST5605 todetermine one BW (ST5607). The mobile terminal then notifies the resultof the determination to the base station.

By using one of methods, such as the above-mentioned, the number of UEswhich transmit with the same BW can be controlled, and the increase inthe total receive power of the base station can be prevented.Furthermore, a frequency which a UE at the cell edge can allocate as anuplink frequency can be set up beforehand, and the uplink communicationpath quality at a frequency band to actually know can be acquired.Furthermore, by expecting and selecting a good BW of the uplink from thedownlink CQI, the uplink communication path quality can be acquired withradio resources which are most stabilized for the mobile terminal UE.

The above-mentioned determining method of determining one BW for aSounding RS which serves as an uplink scheduling request SR which themobile terminal uses (the method of determining one BW for Sounding RSin the case of notifying an uplink scheduling request SR by using aSounding RS) can also be applied to Embodiment 8, Embodiment 9, andEmbodiment 10.

A concrete method of allocating radio resources for use in a basestation and a mobile terminal, in ST5103 of the sequence of FIG. 36,will be explained.

FIG. 38 is a figure showing a method of allocating radio resources in acase in which the base station sets up a plurality of BWs for a SoundingRS for measurement (usually) of the communication quality of the uplink,and the circumstances of allocation of radio resources to the mobileterminal UE1 after a transmission request occurs. In FIG. 38, the radioresources which the base station manages are divided into threetime-frequency regions whose bandwidths are expressed as BW#1, BW#2, andBW#3, respectively. A UE group A including a mobile terminal UE1 isallocated to the time-frequency region of BW#1, a UE group B issimilarly allocated to the time-frequency region of BW#2, and a UE groupC is similarly allocated to the time-frequency region of BW#3. In thefigure, reference numeral 531 denotes a data region of the UE group A,reference numeral 532 denotes a sounding (Sounding RS) region of the UEgroup A, reference numeral 533 denotes an RS region for demodulation(Demoduration) of the UE group A, reference numeral 534 denotes a dataregion of the UE group B, reference numeral 535 denotes a sounding(Sounding) RS region of the UE group B, and reference numeral 536denotes an RS region for demodulation (Demoduration) of the UE group B.In this figure, the Sounding RS region is placed in two SBs within 2TTIs, like in the example of FIG. 35( a), and its bandwidth is the sameas the bandwidths (BW#1, BW#2, and BW#3) of the plurality oftime-frequency regions respectively set for the plurality of UE groups.Each of the data region and the RS region for Demoduration in each UEgroup region is divided into a plurality of parts for the respective UEsin each UE group.

A case in which, for example, the UE 1 included in the UE group Adesires to transmit an uplink scheduling request signal SR in a subframe(1) of TTI #1 under the radio resources allocation conditions of FIG. 38is shown in FIG. 38( b). Reference numeral 537 denotes a sounding(Sounding) RS region which serves as a scheduling request signal SR ofthe UE1, reference numeral 538 denotes a transmission data region afterthe UE1 starts data transmission, reference numeral 539 denotes an RSregion for demodulation (Demoduration) of the UE1, and reference numeral540 denotes a sounding (Sounding) RS region for measurement (usually) ofthe uplink communication quality of the UE1. The UE1 transmits aSounding RS which serves as a scheduling request SR with an SB1 (537)which is allocated as a Sounding RS of the UE group A. The BW of the SB537 which is used for a Sounding RS which serves as a scheduling requestsignal SR of the UE1 is the same as the BW#1 of Sounding RS of the UEgroup A. Because the UE1 is not performing any transmission of uplinkdata in the subframe (1), the region which the UE1 uses at that time isonly the SB1. That is, there is no transmission from the UE1 with LBs(LB1, LB2, LB3, LB4, and LB5) and SBs (SB2) other than the SB1 of thesubframe (1). After that, the base station carries out an uplinkscheduling process.

In this case, while 3 TTIs elapse, allocation of radio resources fortransmission of uplink data is notified from the base station to theUE1, and the UE1 starts transmission of uplink data from the subframe(7). After that, the data 538 for the UE1 are allocated to the LBs 1 to6, the uplink Sounding RS 540 for measurement (usually) of the uplinkcommunication quality of the UE1 is allocated to the SB1 in TTI#4 andthe SB2 in TTI#5, and the RS for demodulation is allocated to theremaining SBs. As shown in the figure, the BW of the region of theuplink Sounding RS which serves as a scheduling request SR of the UE1,and the BW of the region of the uplink Sounding RS for measurement(usually) of the communication quality of the uplink are the same as thebandwidth BW#1 of the UE group A, and all mobile terminals UE of the UEgroup A in a data transmission state allocate the same region having thecompletely same timing as this region for transmission of an uplinkSounding RS. In contrast, the bandwidth of the data region of the UE1and that of the region allocated to a Demoduration RS are smaller thanBW#1, and, as these regions, regions distinguished from those of otherUEs are used.

Thus, the timing of transmission of an uplink Sounding RS which servesas an uplink scheduling request signal SR has to be synchronized withthat of transmission of an uplink Sounding RS of another UE (there canbe two or more other UEs) under transmission to which the same BW isallocated.

FIG. 42 shows in greater detail how each of a plurality of UEs is usingradio resources allocated thereto at the same timing in thetime-frequency region allocated to the UE group A. Unlike in the case ofFIG. 38, in the case of FIG. 42, the region for uplink Sounding RS isplaced in two LBs (LB1 in a first subframe, and LB6 in a secondsubframe) within 2 TTIs, like in the case of FIG. 35( b). In the figure,reference numeral 571 denotes a Sounding RS region of the UE group A,reference numeral 572 denotes an RS region for Demoduration of the UEgroup A, reference numeral 573 denotes a data region of the UE group A,reference numeral 574 denotes a Sounding RS region of the UE group B,reference numeral 575 denotes an RS region for Demoduration of the UEgroup B, reference numeral 576 denotes a data region of the UE group B,reference numeral 577 denotes a region of a Sounding RS which serves asan scheduling request signal SR of the UE1 for a start of transmissionof uplink data, and a region of a Sounding RS of the UE2 undertransmission, reference numeral 578 denotes a Demoduration RS region ofthe UE2, reference numeral 579 denotes a data region of the UE2,reference numeral 580 denotes a general Sounding RS region of the UE1and the UE2, reference numeral 581 denotes an RS region for Demodurationof the UE1, and reference numeral 582 denotes a data region of the UE1under transmission.

Hereafter, it is assumed that in the two mobile terminals UE1 and UE2 inthe same UE group A, at a time, the UE1 tries to start uplinktransmission and the UE2 has been transmitting uplink data. The LB1 577which is allocated to the uplink Sounding RS region which all the mobileterminals of the UE group A use at the time of uplink transmission isused, in the UE1, for transmission of an uplink Sounding RS which servesas an uplink scheduling request signal SR notified from the mobileterminal to a base station for a start of uplink transmission, and is,in the UE2, used for transmission of an uplink Sounding RS used forusual measurement of the quality in a base station. As shown in thefigure, these two UEs transmit uplink Sounding RSs having differentmeanings with the same block (LB) of the completely same bandwidth(=BW#1) at the completely same timing.

When receiving this LB1, the base station demodulates the block withcodes which are respectively generated from the sequence numbers of theUEs to receive the uplink Sounding RSs from the UE1 and the UE2. Thebase station then uses the Sounding RS signal from the UE1 from whichthe base station has not received any uplink data signal until now formeasurement of the uplink quality of the UE1, and judges that thisSounding RS signal is a notification (an uplink scheduling requestsignal SR) of a start of transmission by the UE1. In contrast, the basestation uses the Sounding RS signal from the UE2 from which the basestation has so far received an uplink data signal at regular intervalsfor measurement of the uplink quality of the UE2.

The region for data and the region for a Demoduration RS which areallocated while each of the UE1 and the UE2 carries out transmission areallocated to regions which are separated from each other, respectively,as shown in FIG. 42, unlike that for an uplink Sounding RS.

Furthermore, a time-frequency region via which an uplink Sounding RS canbe transmitted is not configured similarly for any UE group, asexplained with reference to FIGS. 38 and 42, and therefore there is alsoprovided a method of configuring a different time-frequency region foreach UE group. FIGS. 43( a) and 43(b) show examples in each of which theregion to which an uplink Sounding RS is allocated is configured foreach UE group in such a way that the time and frequency of the regionare shifted in units of a resource unit (RU). FIG. 43( a) shows theexample in which, in a case in which the BW of a Sounding RS is equal tothe entire bandwidth of the base station, the region with which anuplink Sounding RS can be transmitted is allocated in the time-frequencyregion in such a way that the region differs for each UE group. Thefigure shows an example in which time sections during each of which aSounding RS can be transmitted are allocated to the four UE groups insuch a way that each of the time sections has a length of 2 TTIs and thetime sections are shifted from one another by 1 TTI. More concretely,among the four UE groups, a UE in the team 1 transmits an uplinkSounding RS during a time section A of TTIs (1) and (2), a UE in theteam 2 transmits an uplink Sounding RS during a time section B of TTIs(2) and (3), a UE in the team 3 transmits an uplink Sounding RS during atime section C of TTIs (3) and (4), and a UE in the team 4 transmits anuplink Sounding RS during a time section D of TTIs (4) and (5). Theallocation is not limited to this example.

Furthermore, as explained in this Embodiment 7, the allocation of anuplink Sounding RS to a region is not limited to allocation to twoblocks within 2 TTIs. As an alternative, the allocation can be carriedout for each TTI, or the allocation can be carried out in such a waythat an uplink Sounding RS is allocated to a predetermined fixed numberof blocks over three or more subframes. Furthermore, there is nonecessity to configure the time sections during each of which a SoundingRS can be transmitted in such a way that they are shifted from oneanother by 1 TTI, and what is necessary is just to configure the timesections according to a period which is enough to reduce the networkload and to maintain the accuracy of the measurement of the uplinkquality. Because using this method, the time sections during which theplurality of UE teams can transmit uplink sounding RSs respectivelydiffer from one another, the number of UEs which the base stationreceive simultaneously can be reduced.

Furthermore, the distribution of the total transmit power of the basestation can be optimized.

FIG. 43( b) shows the example in which, in a case in which a pluralityof BWs are configured an uplink Sounding RS, the time section duringwhich an uplink Sounding RS can be transmitted is allocated in each ofthe time-frequency regions of the BWs in such a way that the timesection differs for each UE group. Because using this method, thefrequency bands with which the plurality of UE teams perform uplinktransmissions respectively and the time sections during which theplurality of UE teams can transmit uplink sounding RSs respectivelydiffer from one another, compared with FIG. 43( a), the number of UEswhich the base station receive simultaneously with the same band at thetime of reception can be reduced and the receiving load of the wirelesscommunication unit of the base station can be reduced. Furthermore, thedistribution of the total transmit power of the base station can beoptimized.

The method of setting up the BW of an uplink Sounding RS, and allocatingradio resources, which is explained in this Embodiment 7, can also beapplied to a case in which when there exist no transmission of uplinkdata and a Sounding RS is transmitted for the purpose of transmitting asignal other than an uplink scheduling request signal SR. Furthermore,the method of configuring the BW of an uplink Sounding RS, andallocating radio resources, which is explained in this Embodiment 7, canalso be applied to Embodiment 8, Embodiment 9, and Embodiment 10.

The transmit power when transmitting a Sounding RS which serves as anuplink scheduling request signal SR has to be set to be equal to orhigher than that at the time of transmitting a general uplink SoundingRS in view of the importance of the signal. For example, there is alsoprovided a method of acquiring the transmit power of a Sounding RS whichserves as an uplink scheduling request signal SR by using apredetermined equation as follows:

$\begin{matrix}{P_{SR} = {P_{Sounding} + {\frac{E/N_{SR}}{E/N_{Sounding}} \times {k\left( \begin{matrix}\begin{matrix}\begin{matrix}\begin{matrix}\begin{matrix}{{k\text{:}{Constant}}} \\\begin{matrix}{{P_{SR}\text{:}{Transmit}\mspace{20mu} {Power}\mspace{20mu} {of}\mspace{14mu} {Sounding}}\mspace{104mu}} \\{{{Serving}\mspace{20mu} {as}\mspace{25mu} {Scheduling}\mspace{20mu} {Request}}\mspace{76mu}}\end{matrix}\end{matrix} \\{{P_{Sounding}\text{:}{Transmit}\mspace{25mu} {Power}\mspace{20mu} {of}\mspace{14mu} {Uplink}}{\mspace{56mu} \mspace{25mu}}}\end{matrix} \\{{{Sounding}\mspace{20mu} {RS}}\mspace{135mu}}\end{matrix} \\\begin{matrix}{{E\text{/}{N_{SR}:{E_{b}\text{/}{No}\mspace{20mu} {of}\mspace{20mu} {Uplink}\mspace{14mu} {Sounding}}}}} \\{{{RS}\mspace{20mu} {Serving}\mspace{20mu} {as}\mspace{20mu} {Scheduling}\mspace{20mu} {Request}}\mspace{11mu}}\end{matrix}\end{matrix} \\{E\text{/}{N_{Sounding}:{E_{b}\text{/}{No}\mspace{20mu} {of}\mspace{14mu} {Uplink}\mspace{20mu} {Sounding}\mspace{14mu} {RS}}}}\end{matrix} \right.}}}} & \left\lbrack {{Equation}\mspace{20mu} 1} \right\rbrack\end{matrix}$

As mentioned above, by, for example, setting up the transmit powers ofmobile terminals according to their respective desired power-to-noiseratios so as to make the transmit power of each mobile terminal at thetime of transmitting a Sounding RS which serves as an uplink schedulingrequest signal SR be equal to or larger than that at the time oftransmitting a general uplink Sounding RS, erroneous reception of uplinkscheduling request signals by the base station can be reduced. Asmentioned above, the method of setting up the transmit power of aSounding RS which serves as an uplink scheduling request signal SR canalso be applied to Embodiment 8, Embodiment 9, and Embodiment 10.

As mentioned above, when a transmission request occurs in a case inwhich a mobile station is synchronized with a base station, and notransmission of uplink data is being carried out and no allocation of anAck/Nack exclusive channel is made, a frequency band wider than that atthe time of using an S-RACH can be used by transmitting an uplinkscheduling request signal SR by using a Sounding RS for measurement ofthe quality of the uplink. Therefore, transmission further resistant tothe frequency selective fading can be implemented. Because by using a“sounding RS which serves as an uplink scheduling request signal SR”, anuplink communication path quality measurement in the base station can becarried out while serving as transmission of an uplink schedulingrequest signal SR. Therefore, the necessity to transmit a sounding RSfor measurement of the uplink quality independently from a schedulingrequest signal SR can be eliminated. Furthermore, because a widefrequency band is used, it is easy to incorporate the communicationquality of the uplink into subsequent uplink scheduling. In addition,the radio resources of the S-RACH can be released, and the complexity inthe uplink scheduling sequence between the mobile terminal and the basestation can be reduced.

Embodiment 8

Even in a case in which a mobile terminal is synchronized with a basestation, and is not receiving downlink data (Downlink data, DL data)transmitted from a base station, or allocation of an Ack/Nack exclusivechannel for transmitting an Ack/Nack signal or a CQI signal which is theresult of reception of downlink data to the base station is not made andthe mobile terminal is not carrying out any transmission of uplink data(Uplink data, UL data) such as user data, the mobile terminal maytransmit a reference signal for sounding (a reference signal formeasurement of the quality of an uplink communication path) to the basestation at certain periodicity in order to maintain uplinksynchronization with the base station. A case in which a mobile terminaltransmits a reference signal 7901 for sounding at certainperiodicity(n×TTI) is shown in FIG. 53. On the other hand, when anecessity to transmit uplink data occurs in the mobile terminal, themobile terminal has to transmit an uplink scheduling request signal SRto the base station separately.

Therefore, there may be a case in which an uplink scheduling requestsignal SR and a reference signal for sounding are transmittedsimultaneously. When transmitted simultaneously, they are nottransmitted with single carrier transmission, but are transmitted withmulti carrier transmission. In the case in which such signals having nocorrelation among them are transmitted simultaneously, the PAPR becomeshigh because the time waveforms of the transmission signals have a highpeak. A problem is that as the PAPR becomes high, the power consumptionof the mobile terminal increases and therefore the cell coverage becomesnarrow. A further problem is that as the PAPR becomes high, thosesignals become an interference wave to other mobile terminals and thecommunication system. In order to avoid these problems, there can beconsidered a measure of shifting the transmission timing of a referencesignal for sounding from that of an uplink scheduling request signal SR,or the like, though the scheduling control in the base station and/orthe mobile terminal becomes complicated.

In this Embodiment 8, a method of making a reference signal for soundingserve as an uplink scheduling request signal SR in order to solve theabove-mentioned problems will be explained.

In above-mentioned Embodiment 7, the transmission method of transmittinga scheduling request in a state in which a mobile terminal does nottransmit a reference signal for sounding in a case in which the mobileterminal is not transmitting uplink data is disclosed. In that case, thebase station judges that there is a scheduling request when receiving areference signal for sounding. Therefore, the base station does not haveto have a function of judging whether a reference signal for soundingserves as an uplink scheduling request, and/or a function of judgingwhether or not there occurs scheduling.

However, there arises anew problem that in a case in which a mobileterminal transmits a reference signal for sounding at certainperiodicity, in order to make the reference signal for sounding serve asan uplink scheduling request signal SR, the base station has to judgewhether the received signal is the one sounding or the one for uplinkscheduling, and/or has to judge whether or not there occurs scheduling.In order to solve this problem, in this Embodiment 8, a method ofproviding two types of pilot patterns for sounding, definingcorrespondences between these two types of pilot patterns and thepresence and absence of an uplink scheduling request, and transmittingone of the two types of pilot patterns according to the presence orabsence of an uplink scheduling request is disclosed (refer to FIG. 80).

A method of, in a case in which a mobile terminal transmits a referencesignal for sounding, allocating a pilot for sounding, and allocating acode specific to each mobile terminal is shown in FIG. 46. Referencenumeral 7201 denotes the pilot for sounding, and reference numeral 7202denotes the code specific to each mobile terminal. When the mobileterminal transmits the reference signal for sounding, the encoder unitor the modulating unit of the mobile terminal multiplies the pilot forsounding by the code specific to each mobile terminal to generate thereference signal for sounding.

After the reference signal for sounding is subjected to a modulationprocess and is converted into a baseband signal, the reference signalfor sounding is converted into a signal having a radio frequency. Afterthat, the reference signal for sounding is transmitted to the basestation by way of an antenna. The code specific to each mobile terminalis used by the base station in order for the base station to, whenreceiving reference signals for sounding from a plurality of mobileterminals, identify which one of the reference signals for sounding isthe one from the above-mentioned mobile terminal. It is preferable thatthe above-mentioned code is the one having orthogonality, or this codeyields multiplication of a pilot pattern thereby having orthogonality.

As an alternative, the above-mentioned code can be a spread code or ascramble code. A time-frequency region to which the reference signal forsounding is allocated is predetermined or is notified from the basestation. A frequency region can have one of various bands. A time regioncan be provided once during each TTI or during several TTIs. Acorrelation operation is performed on the reference signal for soundingwhich the base station has received by using a code specific to eachmobile terminal, and, by using a code which yields a correlationoperation result which is equal to or larger than a threshold, the basestation can identify the mobile terminal. The base station restarts thesynchronization of an uplink channel with the mobile terminal which thebase station has identified by using the reference signal for sounding.The base station can also measure the uplink communication path qualityby using the above-mentioned signal.

One embodiment of making a reference signal for sounding have thefunctions of an uplink scheduling request signal SR will be disclosedhereafter. A method of generating a reference signal for sounding havingthe functions of an uplink scheduling request signal SR is shown in FIG.44. Reference numeral 7001 denotes a pilot pattern 1 for sounding,reference numeral 7002 denotes a pilot pattern 2 for sounding, referencenumeral 7003 denotes a switch for switching between the two types ofpatterns, reference numeral 7004 denotes a control unit for controllingthe switch, and reference numeral 7005 denotes a code specific to eachmobile terminal. Each of the above-mentioned pilots 1 and 2 for soundingcan be a single symbol or can be a plurality of symbols. It ispreferable that the above-mentioned code is the one havingorthogonality, or this code yields multiplication of a pilot patternthereby having orthogonality. As an alternative, the above-mentionedcode can be a spread code or a scramble code. However, in a case inwhich the code is a scramble code, it is preferable that each of theabove-mentioned pilots 1 and 2 for sounding is a plurality of symbols.

As the pilot patterns for sounding, there are provided two types ofpatterns according to the presence and absence of an uplink schedulingrequest. As shown in a table of the figure, in a case in which there isno uplink scheduling request, the pattern 1 is allocated in advance,whereas in a case in which there is an uplink scheduling request, thepattern 2 is allocated in advance.

FIG. 45 shows a diagram of sequences between the mobile terminal and thebase station. The mobile terminal transmits a reference signal forsounding at certain periodicity. A time-frequency region to which thereference signal for sounding is allocated is predetermined or isnotified from the base station. The mobile terminal, in ST7101, judgeswhether an uplink data transmission request has occurred. When no uplinkdata transmission request has occurred, the mobile terminal carries outST7102 because the mobile terminal does not transmit any schedulingrequest. The control unit 7004, in ST7102, changes the state of theswitch 7003 in such a way as to select the pilot pattern 1 for sounding.

In contrast, when an uplink data transmission request has occurred, themobile terminal carries out ST7103 because the mobile terminal transmitsan uplink scheduling request. The control unit 7004, in ST7103, changesthe state of the switch 7003 in such a way as to select the pilotpattern 2 for sounding. The mobile terminal, in ST7104, multiplies thepilot pattern for sounding selected in either of the cases by the code7005 specific to each mobile terminal to generate a reference signal forsounding. The mobile terminal, in ST7105, performs a modulation process,baseband signal conversion, and radio frequency conversion on thereference signal for sounding, and transmits the reference signal forsounding to the base station with the time-frequency region allocated tothe reference signal for sounding by way of the antenna. The basestation, in ST7106, receives the reference signal for sounding. The basestation, in ST7107, performs a correlation operation on this referencesignal for sounding with the code specific to each mobile terminal, andidentifies the mobile terminal when the result of the operation is equalto or larger than a threshold.

Next, the base station, in ST7108, judges whether the pilot for soundinghas the pattern 1 or the pattern 2. When judging that the pilot forsounding has the pattern 1, the base station, in ST7109, carries out theprocessing by judging that there does not occur uplink scheduling. Incontrast, when judging that the pilot for sounding has the pattern 2,the base station, in ST7110, carries out a process in the case in whichthere occurs uplink scheduling.

When, in ST7107, the result of the correlation operation is smaller thanthe threshold, the base station ends the processing by judging that thereference signal for sounding has been transmitted thereto from anothermobile terminal other than the above-mentioned mobile terminal.

In one example of the two types of pilot patterns for sounding whichenable the base station to judge whether the pilot for sounding has thepattern 1 or the pattern 2, a code and a reverse code are allocated tothe pilot pattern 1 and the pilot pattern 2, respectively (when acertain symbol allocated to one of them is “1”, “0” is allocated to theother one). By carrying out the allocation of codes to the two types ofpilot patterns in this way, the base station, in ST7108, can judgewhether the pilot for sounding is the pilot 1 or the pilot 2 by judgingwhether the result of the correlation operation is positive or negative.

The base station can also restart the synchronization of the uplinkchannel with this identified mobile terminal by using the pilot pattern1 or 2 for sounding.

With the above-mentioned structure, the mobile terminal can suppress theincrease in the PAPR which appears when transmitting an uplinkscheduling request signal SR and a reference signal for soundingsimultaneously.

Furthermore, because it becomes unnecessary to ensure the region of anS-RACH for a scheduling request, the waste of the time-frequencyresource can be eliminated.

In addition, because the mobile terminal does not have to carry out aprocess of shifting the transmission timing of a reference signal forsounding and that of an uplink scheduling request signal SR from eachother, and so on, the scheduling control in the base station and/or themobile terminal can be prevented from becoming complicated.

Furthermore, by forming a reference signal for uplink sounding in such away that the reference signal for uplink sounding serves as an uplinkscheduling request signal SR, as mentioned above, the base station isenabled to, when receiving this signal, judge whether this signal has anuplink scheduling request.

In addition, because only one type of specific code has only to beallocated to each mobile terminal, many code resources can be ensuredand the number of mobile terminals from which the base station canreceive signals simultaneously can be increased.

Furthermore, because a frequency band wider than that at the time ofusing an S-RACH or an Ack/Nack exclusive channel can be used,transmission further resistant to the frequency selective fading can beimplemented.

Hereafter, variants will be explained.

In a first variant, a symbol of the pilot for sounding is a symbol forscheduling request. A pilot pattern in which a part of the pilot forsounding is a symbol for scheduling request is shown in FIG. 47.

When there is no scheduling request, 1 is allocated to the symbol forscheduling request, whereas when there is a scheduling request, 0 isallocated to the symbol for scheduling request.

This variant will be explained with reference to a sequence diagram ofFIG. 48. The mobile terminal, in ST7401, judges whether an uplink datatransmission request has occurred. When no uplink data transmissionrequest has occurred, the mobile terminal carries out ST7402 because themobile terminal does not transmit any scheduling request. The mobileterminal, in ST7402, sets 1 to the symbol for scheduling request. Incontrast, when an uplink data transmission request has occurred, themobile terminal carries out ST7403 because the mobile terminal transmitsa scheduling request. The mobile terminal, in ST7403, sets 0 to thesymbol for scheduling request. The mobile terminal, in ST7404,multiplies the pilot pattern for sounding selected in either of thecases by a code A specific to each mobile terminal to generate areference signal for sounding.

The mobile terminal, in ST7405, performs a modulation process, basebandsignal conversion, and radio frequency conversion on the referencesignal for sounding, and transmits the reference signal for sounding tothe base station with the time-frequency region allocated to thereference signal for sounding by way of the antenna. The base station,in ST7406, receives the reference signal for sounding. The base station,in ST7407, performs a correlation operation on this reference signal forsounding with the code A specific to each mobile terminal, andidentifies the mobile terminal when the result of the operation is equalto or larger than a threshold. Next, the base station, in ST7408, judgeswhether the symbol for scheduling request is 1 or 0. When judging thatthe symbol for scheduling request is 1, the base station, in ST7409,carries out the processing by judging that there does not occur uplinkscheduling. In contrast, when judging that the symbol for schedulingrequest is 0, the base station, in ST7410, carries out a process in thecase in which there occurs uplink scheduling.

The number of symbols which are used for a scheduling request can be oneor can be two or more. By using two or more symbols for a schedulingrequest, there can be provided an advantage of increasing the compositeelectric power in the base station and therefore reducing the errorrate.

Furthermore, the symbols for sounding can be multiplied by a codespecific to each mobile terminal according to the number of the symbolsfor sounding and the one or more symbols for scheduling request can bemultiplied by another code specific to the mobile terminal according tothe number of the symbols for scheduling request, and the referencesignal for sounding and scheduling request can be multiplexed withrespect to time. Thereby, a scrambling code can be used as the codespecific to each mobile terminal. Furthermore, because the base stationcan perform the correlation operation by using only the reference signalfor sounding, there is provided an advantage of improving thesynchronization accuracy and the accuracy of evaluation of channelconditions (the quality of the uplink communication path). In addition,in a case in which the number of the symbols for sounding is the same asthe number of the one or more symbols for scheduling request, both ofthem can be multiplied by an identical code specific to each mobileterminal. Thereby, there is provided an advantage of making effectiveuse of the code resources.

In a second variant, two codes specific to each mobile terminal areprepared, and the pilot for sounding is multiplied by one of the twocodes specific to each mobile terminal which is according to thepresence or absence of an uplink scheduling request.

An example of generation of a reference signal for sounding is shown inFIG. 49. Reference numeral 7501 denotes a pilot for sounding, referencenumeral 7503 denotes a code A specific to each mobile terminal,reference numeral 7504 denotes another code B specific to each mobileterminal, reference numeral 7502 denotes a switch for selecting a codeby which the pilot for sounding is multiplied, and reference numeral7505 denotes a control unit for transmitting a signal for selecting acode (7503 or 7504) according to the presence or absence of a schedulingrequest by using the switch 7502. As shown in a table of the figure, asthe code specific to each mobile terminal, when there is no uplinkscheduling request, the code A is allocated, whereas when there is anuplink scheduling request, the code B is allocated.

The operation of the variant will be explained with reference to asequence diagram of FIG. 50. The mobile terminal, in ST7601, judgeswhether an uplink data transmission request has occurred. When no uplinkdata transmission request has occurred, the mobile terminal carries outST7602 because the mobile terminal does not transmit any schedulingrequest. The mobile terminal, in ST7602, selects the code A by using theswitch 7502 according to a control signal from the control unit 7505 insuch a way as to carry out multiplication with the code A. As a result,the pilot for sounding is multiplied by the code A 7503. In contrast,when an uplink data transmission request has occurred, the mobileterminal carries out ST7603 because the mobile terminal transmits ascheduling request. The mobile terminal, in ST7603, selects the code B7504 by using the switch 7502 according to the control signal from thecontrol unit 7505 in such a way as to carry out multiplication with thecode B. As a result, the pilot for sounding is multiplied by the code B.

The mobile terminal, in ST7604, performs a modulation process, basebandsignal conversion, and radio frequency conversion on the referencesignal for sounding, and transmits the reference signal for sounding tothe base station with the time-frequency region allocated to thereference signal for sounding by way of the antenna. The base station,in ST7605, receives the reference signal for sounding. The base station,in ST7606, performs a correlation operation on this reference signal forsounding with the code A first, and identifies the mobile terminal whenthe result of the operation is equal to or larger than a certainthreshold, though the base station handles the reference signal forsounding by judging that the reference signal does not include ascheduling request. In contrast, when the result of the operation issmaller than the certain threshold, the base station, in ST7608,performs a correlation operation on the above-mentioned reference signalfor sounding with the code B. When the result of the operation is equalto or larger than a certain threshold, the base station identifies themobile terminal and then handles the reference signal for sounding byjudging that the reference signal includes a scheduling request.

When, in ST7606, the result of the correlation operation with the code Ais less than the certain threshold, and when, in ST7608, the result ofthe correlation operation with the code B is less than the certainthreshold, the base station judges that the reference signal forsounding is the one from another mobile terminal other than the mobileterminal, and ends the processing.

Because this variant is constructed as mentioned above, there isprovided an advantage of eliminating the necessity to provide two typesof pilot patterns for sounding, and a further advantage of eliminatingthe necessity to judge whether the result of each correlation operationis positive or negative because an orthogonal code is also used forjudgment of the presence or absence of a scheduling request.Furthermore, because an orthogonal code is also used for judgment of thepresence or absence of a scheduling request, there is provided anotheradvantage of improving the judgment precision, the synchronizationaccuracy, and the accuracy of evaluation of channel conditions.

In a third variant, one type of code for judgment of the presence orabsence of a scheduling request is prepared, and there is provided amethod of controlling whether to carry out multiplication with this codeaccording to the presence or absence of an uplink scheduling request.

An example of generation of a reference signal for sounding is shown inFIG. 51. Reference numeral 7701 denotes a pilot for sounding, referencenumeral 7703 denotes a code a for judgment of the presence or absence ofa scheduling request, reference numeral 7702 denotes a switch forselecting whether to multiply the sounding pilot by the code a,reference numeral 7705 denotes a control unit for transmitting a signalindicating whether to multiply the sounding pilot by the code a with theswitch 7702, and reference numeral 7704 denotes a code specific to eachmobile terminal. As shown in a table of the figure, when there is nouplink scheduling request, the code for judgment of the presence orabsence of a scheduling request is not allocated, whereas when there isan uplink scheduling request, the code a is allocated.

The operation of this variant will be explained with reference to asequence diagram of FIG. 52. The mobile terminal, in ST7801, judgeswhether an uplink data transmission request has occurred. When no uplinkdata transmission request has occurred, the mobile terminal performs aselection so as not to carry out multiplication by the code a by usingthe switch 7702 according to the control signal from the control unit7705 because the mobile terminal does not transmit any schedulingrequest, and then carries out ST7803. In contrast, when an uplink datatransmission request has occurred, the mobile terminal carries outST7802 because the mobile terminal transmits a scheduling request. Themobile terminal, in ST7802, selects the code a 7703 by using the switch7702 according to the control signal from the control unit 7705 in sucha way as to carry out multiplication with the code a. As a result, thepilot for sounding is multiplied by the code a for judgment of thepresence or absence of a scheduling request. In ST7803, the pilot forsounding is multiplied by the code A specific to each mobile terminal.

The mobile terminal, in ST7804, performs a modulation process, basebandsignal conversion, and radio frequency conversion on the referencesignal for sounding, and transmits the reference signal for sounding tothe base station with the time-frequency region allocated to thereference signal for sounding by way of the antenna. The base station,in ST7805, receives the reference signal for sounding. The base station,in ST7806, performs a correlation operation on this reference signal forsounding with the code A specific to each mobile terminal, andidentifies the mobile terminal when the result of the operation is equalto or larger than a threshold.

The base station then, in ST7807, performs a correlation operation onthe above-mentioned reference signal for sounding with the code a, and,when the result of the operation is equal to or larger than a threshold,handles the reference signal for sounding by judging that the referencesignal has a scheduling request. In contrast, when the result of theoperation is smaller than the threshold, the base station handles thereference signal for sounding by judging that the reference signal doesnot include a scheduling request.

The scheduling request presence or absence identification code a and thecode A specific to each mobile terminal can be scramble codes or spreadcodes.

Because this variant is constructed as mentioned above, there isprovided an advantage of eliminating the necessity to judge whether theresult of each correlation operation is positive or negative because anorthogonal code can also be used for judgment of the presence or absenceof a scheduling request. Furthermore, because an orthogonal code is alsoused for judgment of the presence or absence of a scheduling request,there is provided another advantage of improving the judgment precision.In addition, there is provided a further advantage of eliminating thenecessity to double the amount of codes specific to each mobileterminal, unlike the second variant.

As mentioned above, with the structure as mentioned in this Embodiment8, the mobile terminal can suppress the increase in the PAPR whichappears when transmitting an uplink scheduling request signal SR and areference signal for sounding simultaneously.

Furthermore, because it becomes unnecessary to ensure the region of anS-RACH for a scheduling request, the waste of the time-frequencyresource can be eliminated.

In addition, because the mobile terminal does not have to carry out aprocess of shifting the transmission timing of a reference signal forsounding and that of an uplink scheduling request signal SR from eachother, and so on, the scheduling control in the base station and/or themobile terminal can be prevented from becoming complicated.

Furthermore, by forming a reference signal for uplink sounding in such away that the reference signal for uplink sounding serves as an uplinkscheduling request signal SR, as mentioned above, the base station isenabled to, when receiving this signal, judge whether this signal has anuplink scheduling request.

In addition, because a frequency band wider than that at the time ofusing an S-RACH or an Ack/Nack exclusive channel can be used,transmission further resistant to the frequency selective fading can beimplemented.

Embodiment 9

When a necessity for transmission of uplink data occurs in a mobileterminal in a state in which the mobile terminal is receiving downlinkdata (Downlink data, DL data) transmitted from a base station or in astate in which allocation of an Ack/Nack exclusive channel fortransmitting an Ack/Nack signal, which is the result of reception ofdownlink data, and/or a CQI signal to the base station is made, themobile terminal has to transmit an uplink scheduling request signal SRto the base station. In this case, the mobile terminal may transmit theAck/Nack signal and/or the CQI signal, and the uplink scheduling requestsignal SR simultaneously. When transmitted simultaneously, they are nottransmitted with single carrier transmission, but are transmitted withmulti carrier transmission. In the case in which such signals having nocorrelation among them are transmitted simultaneously, the PAPR becomeshigh because the time waveforms of the transmission signals have a highpeak. A problem is that as the PAPR becomes high, the power consumptionof the mobile terminal increases and therefore the cell coverage becomesnarrow.

A further problem is that as the PAPR becomes high, those signals becomean interference wave to other mobile terminals and the communicationsystem.

In order to avoid these problems, in Embodiments 1 and 2, the method oftransmitting an uplink scheduling request signal by using an S-RACH, andDTXing an Ack/Nack and/or a CQI signal at the same timing is disclosed.In Embodiments 3 and 4, the method of incorporating an uplink schedulingrequest signal into an Ack/Nack exclusive channel to transmit the uplinkscheduling request signal is disclosed.

In this Embodiment 9, a method of transmitting an uplink schedulingrequest signal by using a region for sounding RS will be disclosed. Inthis Embodiment 9, a case in which there is no sounding RS which istransmitted for uplink timing synchronization at certain periodicitywill be disclosed.

The region for sounding RS is already explained in Embodiment 7. InEmbodiment 7, the case in which no allocation of an Ack/Nack exclusivechannel is made is disclosed. In contrast, in this embodiment, a case inwhich allocation of an Ack/Nack exclusive channel is made will bedisclosed.

FIG. 55 shows a figure of a time-frequency resource in a case in whichthere are regions for an Ack/Nack exclusive channel. Regions A and B areregions for an Ack/Nack exclusive channel. The region for sounding RS isallocated to a region other than channel for Ack/Nack, in this example,the allocation to the first LB is carried out once within 2 TTIs.

Each of a plurality of mobile terminals under the control of the basestation transmits a reference signal for sounding using this region forsounding RS. The plurality of mobile terminals can be divided into oneor more groups. Furthermore, the region for sounding reference symbolscan also be divided into one or more regions. Transmission of an RS forsounding by a mobile terminal included in a certain mobile terminalgroup can be carried out by using a certain divided region.

A transmission signal of a mobile terminal in a case in which ascheduling request occurs is shown in FIG. 60. When a necessity fortransmission of uplink data occurs in a mobile terminal in a state inwhich the mobile terminal is receiving downlink data (Downlink data, DLdata) transmitted from a base station, or in a state in which allocationof an Ack/Nack exclusive channel for transmitting an Ack/Nack signal,which is the result of reception of downlink data, and/or a CQI signalto the base station is made, and the mobile terminal then transmits anuplink scheduling request signal SR to the base station, the mobileterminal transmits the uplink scheduling request signal by using aregion for sounding RS allocated to this mobile terminal, and transmitsan Ack/Nack signal, a CQI signal, or a reference signal for demodulationwith other LBs or SBs by using the Ack/Nack exclusive channel. Incontrast, when there is no uplink scheduling request, the mobileterminal does not transmit an uplink scheduling request signal, buttransmits an Ack/Nack signal and/or a CQI signal by using the Ack/Nackexclusive channel.

FIG. 59 shows mapping of transmission symbols in a mobile terminal inthe case in which the mobile terminal transmits an uplink schedulingrequest signal with the region for sounding RS. A pilot symbol forsounding is inserted into a leading LB within 2 TTIs. An Ack/Nack or aCQI symbol is inserted into other LBs. The pilot for sounding ismultiplied by a code a specific to each mobile terminal which is used inthe region for sounding. This code a is used in order for the basestation to identify from which mobile terminal the base station hasreceived the transmission because the region for sounding is shared by aplurality of mobile terminals. The symbol for sounding which ismultiplied by the code a specific to each mobile terminal, which is usedin the region for sounding, is mapped to the region for sounding RS.

An Ack/Nack or a CQI symbol is multiplied by a code A specific to eachmobile terminal, and is mapped to the Ack/Nack exclusive channel. Thiscode A is used to identify the mobile terminal in the Ack/Nack exclusivechannel, as mentioned in Embodiment 3. These two types of codes specificto each mobile terminal are predetermined, or are notified from the basestation.

FIG. 62 is a sequence diagram. The mobile terminal, in ST8901, judgeswhether an uplink data transmission request has occurred. When no uplinkdata transmission request has occurred, the mobile terminal carries outST8904 because the mobile terminal does not transmit any schedulingrequest. The mobile terminal, in ST8904, inserts an Ack/Nack or a CQIsymbol into each of all LBs within 2 TTIs, and multiplies each of themby the code A. In contrast, when an uplink data transmission request hasoccurred, the mobile terminal carries out ST8902 and ST8903 because themobile terminal transmits a scheduling request.

The mobile terminal, in ST8902, inserts the pilot for sounding into thefirst LB within 2 TTIs, and multiplies this LB by the code a. The mobileterminal, in ST8903, inserts an Ack/Nack and/or a CQI into a second orsubsequent LBs, and multiplies these LBs by the code A. The mobileterminal, in ST8905, carries out allocation of the pilot for soundingwhich is multiplied by the code a to the region for sounding RS, andcarries out allocation of the Ack/Nack or the CQI which is multiplied bythe code A to the Ack/Nack exclusive channel, and then transmits them tothe base station. The base station which, in ST8906, received thesignals, in ST8907, performs a correlation operation on the signal inthe region for sounding by using the code a, and, when the result of thecorrelation operation is equal to or larger than a certain threshold,can identify the mobile terminal and judge that the base station hasreceived an uplink scheduling request from this identified mobileterminal.

The base station which has judged that the base station has received anuplink scheduling request, in ST8910, handles the uplink schedulingrequest. The base station then, in ST8911, performs a correlationoperation on the signal in the second or subsequent LBs or SBs, which istransmitted via the Ack/Nack exclusive channel, by using the code A,and, in ST8912, performs judgment of the Ack/Nack or the CQI. When, inST8907, the result of the correlation operation with the code a issmaller than the certain threshold, the base station still cannotidentify the mobile terminal and handles the signal by judging that thesignal does not have an uplink scheduling request. In that case, thebase station, in ST8909, performs a correlation operation on signals inall the LBs and SBs, which are transmitted via the Ack/Nack exclusivechannel, by using the code A, and, when the result of the correlationoperation is equal to or larger than a certain threshold, identifies themobile terminal. After identifying the mobile terminal, the basestation, in ST8912, performs judgment of the Ack/Nack or the CQI.

With the structure as mentioned above, the mobile terminal can suppressthe increase in the PAPR which appears when transmitting both anAck/Nack signal or a CQI signal, and an uplink scheduling request signalSR simultaneously.

Furthermore, because it becomes unnecessary to ensure the region of anS-RACH for a scheduling request in advance, the waste of thetime-frequency resource can be eliminated.

In addition, by transmitting an uplink scheduling request signal SR byusing a reference signal for sounding, the base station is enabled to,when receiving this signal, judge whether this signal has an uplinkscheduling request.

Furthermore, because the mobile terminal transmits an uplink schedulingrequest signal SR by using a reference signal for sounding, the basestation can evaluate the status of the uplink channel used for carryingout uplink scheduling.

In addition, because a frequency band wider than that at the time ofusing an S-RACH or an Ack/Nack exclusive channel can be used,transmission further resistant to the frequency selective fading can beimplemented.

Furthermore, the base station can measure the status of the frequencyselective fading, and can carry out appropriate uplink scheduling.

In the above-mentioned embodiments, when a mobile terminal does not havean uplink scheduling request, the mobile terminal inserts an Ack/Nack ora CQI symbol into the first LB. As the mapping method, the methoddisclosed in Embodiment 2 can be applied. By doing in this way, there isprovided an advantage of improving the quality of reception of anAck/Nack or a CQI.

As shown in above-mentioned Embodiment 1, also in the case in which amobile terminal has an uplink scheduling request, the mobile terminalcan insert an Ack/Nack or a CQI symbol into each of all the LBs and SBs,like in the case in which there is no uplink scheduling request, and,only when the mobile terminal has an uplink scheduling request, can DTXonly the first LB and transmit a sounding pilot in this LB by using theRS region for sounding. As a result, the complexity of the process ofmultiplexing symbols can be reduced.

In the above-mentioned embodiments, the case in which an Ack/Nack and/ora CQI signal is transmitted by using an Ack/Nack exclusive channel isdisclosed. In contrast, the method of this embodiment can also beapplied to a case in which an Ack/Nack or a CQI signal is nottransmitted by using an Ack/Nack exclusive channel. For example, when ascheduling request occurs in a mobile terminal, the mobile terminal hasonly to transmit an RS for sounding by using the first LB in a regionfor sounding and not to transmit any other signals.

In the above-mentioned embodiments, when a scheduling request occurs ina mobile terminal, the mobile terminal inserts a pilot symbol forsounding into the first LB. The same advantage is acquired even if themobile terminal changes an LB or SB into which the mobile terminalinserts the pilot symbol according to the region allocated to an RS forsounding.

Hereafter, variants will be explained. In a first variant, the regionfor sounding RS is allocated to all the bands. FIG. 56 is a figureshowing a time-frequency resource at the time of allocating the regionfor sounding RS to all the bands of the system. Regions A and B areregions for an Ack/Nack exclusive channel. In this example, the first LBis allocated, as the region for sounding RS, once within 2 TTIs. Each ofa plurality of mobile terminals under the control of the base stationtransmits a reference signal for sounding by using this region forsounding RS. The plurality of mobile terminals can be divided into oneor more groups. Furthermore, the region for a sounding reference signalcan also be divided into one or more regions. Transmission of an RS forsounding by a mobile terminal included in a certain mobile terminalgroup can be carried out by using a certain divided region.

A transmission signal of a mobile terminal in a case in which ascheduling request occurs is shown in FIG. 61. When a necessity fortransmission of uplink data occurs in a mobile terminal in a state inwhich the mobile terminal is receiving downlink data (Downlink data, DLdata) transmitted from a base station, or in a state in which allocationof an Ack/Nack exclusive channel for transmitting an Ack/Nack signal,which is the result of reception of downlink data, and/or a CQI signalto the base station is made, and the mobile terminal then transmits anuplink scheduling request signal SR to the base station, the mobileterminal transmits the uplink scheduling request signal by using aregion for sounding RS allocated to this mobile terminal, and transmitsan Ack/Nack signal, a CQI signal, or a reference signal for demodulationin other LBs or SBs by using the Ack/Nack exclusive channel. Incontrast, when there is no uplink scheduling request, the mobileterminal does not transmit any uplink scheduling request signal, and,furthermore, does not transmit any Ack/Nack signal or any CQI signalonce with the first LB by using the Ack/Nack exclusive channel within 2TTIs. This is because since all the bands of the system are allocated tothe region for sounding RS and some other mobile terminals under thecontrol of the base station transmit sounding RSs with this LB of theAck/Nack exclusive channel, if the mobile transmits an Ack/Nack signalor a CQI signal with this LB, the base station cannot discriminate thisAck/Nack or CQI signal from any other signals.

In the mapping of transmission symbols in the mobile terminal, a pilotfor sounding is inserted when there is an uplink scheduling request,like in the mapping shown in FIG. 59, whereas when there is no uplinkscheduling request, it is preferable to insert either nothing or dummydata into the first LB and not to carry out any transmission with thisLB.

With the above-mentioned structure, this embodiment offers the sameadvantages as those provided by Embodiment 9. Furthermore, the basestation can make an evaluation of uplink channel conditions with a widerband.

In addition, because the base station can make an evaluation of thechannel conditions of an Ack/Nack exclusive channel, there is providedan advantage of performing scheduling of an Ack/Nack signal or a CQIsignal of a mobile terminal to an Ack/Nack exclusive channel with a highdegree of precision.

Furthermore, by dividing the plurality of mobile terminals into one ormore groups, and/or by dividing the region for sounding referencesignals into one or more regions, there is provided an advantage ofbringing greater efficiency to the use of the code resources allocatedto each mobile terminal.

In a second variant, the region for sounding RS is divided into partshaving the same frequency bandwidth as the Ack/Nack exclusive channel,and a divided part is allocated to a certain mobile terminal group.

FIG. 57 shows a figure of a time-frequency resource. Regions A and B areregions for an Ack/Nack exclusive channel. In this example, the first LBis allocated, as the region for sounding RS, once within 2 TTIs. Theregion for sounding RS is divided into parts having the same frequencybandwidth as the Ack/Nack exclusive channel, and a divided part isallocated to a certain mobile terminal group. Each of a plurality ofmobile terminals in the certain mobile terminal group transmits areference signal for sounding by using this divided part of the regionfor sounding RS.

Because the region with which a certain mobile terminal transmits asounding RS has the same frequency bandwidth as the Ack/Nack exclusivechannel, the length of a code for sounding pilot symbols can be made tobe equal to that of a code for an Ack/Nack and/or CQI symbols.Therefore, the necessity to separately provide two codes specific toeach mobile terminal for sounding pilot symbols and for an Ack/Nack orCQI symbols can be eliminated. In other words, the required number oftypes of spread codes can be reduced to one.

Therefore, with this structure, there is provided an advantage of beingable to reduce the amount of codes specific to each mobile terminal, andhence to increase the number of mobile terminals allocated from the basestation.

In a third variant, a region for sounding RS is disposed also in anAck/Nack exclusive channel.

FIG. 58 shows a figure of a time-frequency resource. Regions A and B areregions for the Ack/Nack exclusive channel. In this example, also in theAck/Nack exclusive channel region, the first LB is allocated, as theregion for sounding RS, once within 2 TTIs.

Because the region for sounding RS is disposed in the Ack/Nack exclusivechannel, the necessity to separately provide two codes specific to eachmobile terminal for sounding pilot symbols and for an Ack/Nack or CQIsymbols can be eliminated. That is, the frequency band which ismultiplied by the spread code becomes equal. Therefore, with thisstructure, there is provided an advantage of being able to reduce theamount of codes specific to each mobile terminal, and hence to increasethe number of mobile terminals allocated from the base station.

Furthermore, there is provided an advantage of eliminating the necessityto separately carry out allocation to the time-frequency resources forsounding pilot symbols and for an Ack/Nack and/or CQI symbols at thetime of transmission of a signal, thereby being able to simplify thecontrol of each mobile terminal.

Since Embodiment 9 uses a sounding reference signal for transmitting ascheduling request signal, when combined with above-mentioned Embodiment7, Embodiment 9 can be applied to a mobile terminal regardless ofwhether or not an Ack/Nack exclusive channel is allocated to the mobileterminal. More specifically, what is necessary is just to applyEmbodiment 7 in a case in which any Ack/Nack exclusive channel is notallocated to the mobile terminal, and to apply Embodiment 9 in a case inwhich an Ack/Nack exclusive channel is allocated to the mobile terminal.

This Embodiment 9 discloses the case in which a mobile terminal does nottransmit any sounding RS for uplink timing synchronization at certainperiodicity. Furthermore, when combined with Embodiment 8, Embodiment 9can also be applied to a case in which a mobile terminal transmits asounding RS for uplink timing synchronization at certain periodicity.That is, in Embodiment 9, when receiving transmission of a sounding RSfrom a mobile terminal, the base station can recognize that the mobileterminal has made a scheduling request, though when the mobile terminalhas originally transmitted a sounding RS for uplink timingsynchronization, the base station cannot discriminate the sounding RSfor uplink timing synchronization which the mobile terminal hasoriginally transmitted from any scheduling request. In order to solvethis problem, what is necessary is just to use the method disclosed inEmbodiment 8.

Furthermore, also in the case in which a mobile terminal transmits asounding RS for uplink timing synchronization at certain periodicity,Embodiment 9 can be applied to the mobile terminal regardless of whetheror not an Ack/Nack exclusive channel is allocated to the mobileterminal, when combined with the method disclosed in Embodiment 7.

Embodiment 10

A method of enabling a mobile terminal to transmit an uplink schedulingrequest by using a sounding RS regardless of whether the mobile terminaltransmits a sounding RS for uplink timing synchronization at certainperiodicity will be disclosed.

A time-frequency region for sounding RS is allocated as shown in FIG. 42or 55. FIG. 42 shows a case in which no allocation of resources of anAck/Nack exclusive channel is made, and FIG. 55 shows a case in whichallocation of resources of an Ack/Nack exclusive channel is made. Ineither of the cases, a sounding RS from a mobile terminal is transmittedwith an allocated region for sounding RS. It is assumed that the lengthof time intervals at which a sounding RS for uplink timingsynchronization is transmitted is n×TTI (n>=2).

FIG. 63 shows a transmission signal of a mobile terminal when an uplinkscheduling request has occurred. Hereafter, it is assumed that thelength of time intervals at which a sounding RS for uplink timingsynchronization is transmitted is 10TTI. In a case in which a necessityfor transmission of uplink data occurs in a mobile terminal, when thetiming at which the mobile terminal transmits an uplink schedulingrequest is the same as that at which the mobile terminal transmits asounding RS for uplink timing synchronization, the mobile terminaltransmits this sounding RS for synchronization while forming thesounding RS in such a way that the sounding RS have the functions of thescheduling request.

As a method of forming a sounding RS for synchronization in such a waythat the sounding RS have the functions of a scheduling request, themethod disclosed in above-mentioned Embodiment 8 can be used. Forexample, a method of providing two types of sounding pilot patternscorresponding to the presence and absence of an uplink schedulingrequest can be used. In a case in which a necessity for transmission ofuplink data occurs in a mobile terminal, when the timing at which themobile terminal transmits an uplink scheduling request differs from thatat which the mobile terminal transmits a sounding RS for uplink timingsynchronization, the mobile terminal transmits the sounding RS as anuplink scheduling request.

FIG. 64 shows a diagram of sequences between the mobile terminal and thebase station. The mobile terminal, in ST9101, judges whether an uplinkdata transmission request has occurred. When no uplink data transmissionrequest has occurred, the mobile terminal carries out ST9104. Incontrast, when an uplink data transmission request has occurred, themobile terminal, in ST9102, judges whether the transmission timing of anuplink scheduling request is the same as that of a sounding RS foruplink timing synchronization. If those transmission timings are thesame as each other, the mobile terminal carries out ST9103. The mobileterminal, in ST9103, selects a pattern 2 as a pilot for sounding. Themobile terminal then carries out ST9105. When, in ST9102, judging thatthe transmission timing of the uplink scheduling request differs fromthat of a sounding RS for uplink timing synchronization, the mobileterminal carries out ST9104. The mobile terminal, in ST9104, selects apattern 1 as a pilot for sounding. The mobile terminal then carries outST9105. The mobile terminal, in ST9105, multiplies the transmissionsignal by a code A specific to each mobile terminal. The mobileterminal, in ST9106, transmits the transmission signal to the basestation with the region for sounding (RB). The base station which, inST9107, has received the transmission signal with the region forsounding (RB), in ST9108, judges whether or not the received signal hasthe timing of a sounding RS for uplink timing synchronization.

Because the base station carries out scheduling of the timing of asounding RS for uplink timing synchronization and notifies the timing tothe mobile terminal in advance, or the timing is predetermined, the basestation can make the judgment. When, in ST9108, judging that thereceived signal has the same timing, the base station carries outST9110. The base station, in ST9110, performs a correlation operation onthe received signal by using the code A. When the result of thecorrelation operation is equal to or larger than a certain threshold,the base station identifies the mobile terminal. The base station thencarries out ST9111. The base station, in ST9111, judges whether thepilot for sounding is the pattern 1 or the pattern 2. As a method ofjudging whether the pilot for sounding is the pattern 1 or the pattern2, a method disclosed in Embodiment 8 can be used. When judging that thepilot for sounding is the pattern 1, the base station handles the signalby judging that the signal does not include an uplink schedulingrequest. When, in ST9111, judging that the pilot for sounding is thepattern 2, the base station carries out ST9112. When, in ST9108, judgingthat the received signal has a timing different from that of a soundingRS for uplink timing synchronization, the base station carries outST9109. The base station, in ST9109, performs a correlation operation onthe received signal by using the code A, and, when the result of thecorrelation operation is equal to or larger than a certain threshold,the base station identifies the mobile terminal, and, in ST9112, handlesthe signal by judging that the signal includes an uplink schedulingrequest.

With the above-mentioned structure, the same advantages as thoseprovided by Embodiment 8 can be offered. Furthermore, there is providedan advantage of enabling a mobile terminal to transmit an uplinkscheduling request regardless of whether the mobile terminal transmits asounding RS for uplink timing synchronization at certain periodicity.

Hereafter, variants will be explained.

In a first variant, when the transmission timing of an uplink schedulingrequest coincides with that of a sounding RS for uplink timingsynchronization, the timing at which an uplink scheduling request istransmitted is delayed by 2 TTIs.

FIG. 65 shows a transmission signal of a mobile terminal when an uplinkscheduling request occurs in the mobile terminal. In this case, thetransmission time during which a sounding RS for uplink timingsynchronization is transmitted is 10TTI. In a case in which a requestfor transmission of uplink data occurs in a mobile terminal, when thetiming at which the mobile terminal transmits an uplink schedulingrequest is the same as that at which the mobile terminal transmits asounding RS for uplink timing synchronization, the mobile terminaltransmits the scheduling request by delaying its transmission timing by2TTI. In contrast, when the timing at which the mobile terminaltransmits an uplink scheduling request differs from that at which themobile terminal transmits a sounding RS for uplink timingsynchronization, the mobile terminal transmits the scheduling requestwithout delaying its transmission timing by 2TTI.

FIG. 66 shows a diagram of sequences between the mobile terminal and thebase station. The mobile terminal, in ST9301, judges whether an uplinkdata transmission request has occurred. When no uplink data transmissionrequest has occurred, the mobile terminal carries out ST9304. Incontrast, when an uplink data transmission request has occurred, themobile terminal, in ST9302, judges whether the transmission timing of anuplink scheduling request is the same as that of a sounding RS foruplink timing synchronization. If those transmission timings are thesame as each other, the mobile terminal carries out ST9303. The mobileterminal, in ST9303, carries out a process of delaying the transmissiontiming of the scheduling request by 2TTI. In this case, about thesounding RS signal for uplink timing synchronization, the mobileterminal carries out a process of transmitting the sounding RS signalwithout delaying its transmission timing. The mobile terminal, inST9304, multiplies the transmission signal by a code A specific to eachmobile terminal. The mobile terminal, in ST9305, transmits thetransmission signal to the base station with the region for sounding(RB). The base station which, in ST9306, has received the signal withthe RB for sounding carries out ST9307.

The base station, in ST9307, judges whether or not the received signalhas the timing of a sounding RS for uplink timing synchronization. Whenjudging that the received signal has the timing of a sounding RS foruplink timing synchronization, the base station, in ST9308, performs acorrelation operation on the received signal by using the code A, and,when the result of the correlation operation is equal to or larger thana certain threshold, identifies the mobile terminal and then carries outST9309. The base station, in ST9309, handles the signal by judging thatthe signal does not include an uplink scheduling request. Morespecifically, in this case, the base station handles the signal as anormal sounding RS for uplink timing synchronization. When, in ST9307,judging that the received signal has a timing different from that of asounding RS for uplink timing synchronization, the base station, inST9310, performs a correlation operation on the received signal by usingthe code A, and, when the result of the correlation operation is equalto or larger than a certain threshold, the base station identifies themobile terminal and carries out ST9311. The base station, in ST9311,handles the signal by judging that the signal includes an uplinkscheduling request.

With the above-mentioned structure, the same advantages as thoseprovided by Embodiment 10 can be offered. Furthermore, there is providedan advantage of reducing the number of types of sounding pilot patternsto only one. Thereby, there is provided another advantage of reducingthe processing carried out by the base station and the processingcarried out by the mobile terminal. Compared with a case in which in,for example, Embodiment 10, the method of using the two types of codes(the codes A and B), as disclosed in Embodiment 8, is used in order todiscriminate a sounding RS for uplink timing synchronization and anuplink scheduling request from each other, there is provided anadvantage of reducing the number of codes to one-half that in theabove-mentioned case, and increasing the number of mobile terminals toeach of which a mobile-terminal-specific code can be allocated.

In the above-mentioned variant, an uplink scheduling request istransmitted with its transmission timing being delayed by 2TTI. As analternative, an uplink scheduling request can be transmitted at anytiming at which no sounding RS for uplink timing synchronization istransmitted. In this case, a mobile terminal is allowed to transmit ascheduling request with a time delay depending on its processingcapability.

A combination of Embodiment 10 or the first variant with Embodiment 9can be applied regardless of whether or not resource allocation of anAck/Nack exclusive channel is made.

INDUSTRIAL APPLICABILITY

As mentioned above, the present invention is suitable for acommunication system which needs to prevent the increase in the radioresource load due to temporary increase in the physical channels.

1. A data communication method which is implemented by a communicationsystem provided with a base station which transmits data by using anOFDM (Orthogonal Frequency Division Multiplexing) method as a downlinkaccess method, and a mobile terminal which transmits a control signalincluding a response signal corresponding to a result of reception ofthe data transmitted from said base station to said base station, andwhich transmits a scheduling request signal with which to make a requestfor allocation of radio resources to said base station beforetransmitting transmission data to said base station, characterized inthat said mobile terminal carries out a response signal transmissionprocess of transmitting said response signal to said base station byusing an uplink control channel in an uplink direction from said mobileterminal to said base station, a scheduling request signal transmissionprocess of transmitting said scheduling request signal to said basestation by using a physical channel different from said uplink controlchannel when transmission data to be transmitted to said base stationoccur, and a control process of, when a processing timing of saidresponse signal transmission process coincides with that of saidscheduling request signal transmission process, stopping said responsesignal transmission process during a time interval during which saidmobile terminal transmits said scheduling request signal.
 2. The datacommunication method according to claim 1, characterized in that thescheduling request signal is comprised of a preamble including anidentification signal for identifying the mobile terminal which is atransmit source, and a message including at least one of an amount ofthe transmission data transmitted by said mobile terminal, QoS (QualityOf Service) of said transmission data, and a transmit power margin ofsaid mobile terminal.
 3. The data communication method according toclaim 1, characterized in that when performing the scheduling requestsignal transmission process, said mobile terminal selectively performseither a separately transmission process of separately transmitting thepreamble and the message of the scheduling request signal or acollectively transmission process of collectively transmitting saidpreamble and said message.
 4. The data communication method according toclaim 1, characterized in that in the response signal transmissionprocess, a plurality of subframes each comprised of a plurality of datablocks to which data symbols are allocated are included, and said mobileterminal transmits a first subframe and a second subframe during onetransmission time interval, symbols being allocated to the data blocksof each of said first subframe and said second subframe in a samearrangement.
 5. The data communication method according to claim 4,characterized in that in the response signal transmission process, asymbol with a lower priority is allocated to a leading data block of asubframe.
 6. A communications system provided with a base station whichtransmits data by using an OFDM (Orthogonal Frequency DivisionMultiplexing) method as a downlink access method, and a mobile terminalwhich transmits a control signal including a response signalcorresponding to a result of reception of the data transmitted from saidbase station to said base station, and which transmits a schedulingrequest signal with which to make a request for allocation of radioresources to said base station before transmitting transmission data tosaid base station, characterized in that said mobile terminal includes:a transmitting unit for transmitting said response signal to said basestation by using an uplink control channel in an uplink direction fromsaid mobile terminal to said base station, and for transmitting saidscheduling request signal to said base station by using a physicalchannel different from said uplink control channel when transmissiondata to be transmitted to said base station occur; and a control unitfor, when a transmission timing of said response signal coincides withthat of said scheduling request signal in said transmitting unit,stopping the transmission process of transmitting said response signalduring a time interval during which said transmitting unit transmitssaid scheduling request signal.
 7. A data communication method which isimplemented by a communications system provided with a base stationwhich transmits data by using an OFDM (Orthogonal Frequency DivisionMultiplexing) method as a downlink access method, and a mobile terminalwhich transmits a scheduling request signal with which to make a requestfor allocation of radio resources to said base station beforetransmitting transmission data to said base station, characterized inthat said mobile terminal carries out a control signal generationprocess of, when transmission data to be transmitted to said basestation occur, performing time division multiplexing of said schedulingrequest signal and said response signal to generate said uplink controlsignal, or generating said uplink control signal from said schedulingrequest signal, and a control signal transmission process oftransmitting a control signal including said uplink control signalgenerated through said control signal generation process to said basestation by using an uplink control channel in an uplink direction fromsaid mobile terminal to said base station.
 8. The data communicationmethod according to claim 7, characterized in that when the controlsignal generated through the control signal generation process does notinclude the scheduling request signal, the mobile terminal performs acoding process on said control signal by using a first code, whereaswhen said control signal includes said scheduling request signal, themobile terminal performs a coding process on said control signal byusing a second code.
 9. A data communication method which is implementedby a communications system provided with a base station which transmitsdata by using an OFDM (Orthogonal Frequency Division Multiplexing)method as a downlink access method, and a mobile terminal whichtransmits a control signal including a response signal corresponding toa result of reception of the data transmitted from said base station tosaid base station, and which transmits a scheduling request signal tosaid base station, and, when radio resources are allocated thereto bysaid base station in response to the scheduling request signal,transmits individual data by using an uplink common channel,characterized in that said mobile terminal selectively carries outeither a process of coding said individual data by using a first code ora process of coding said individual data including said schedulingrequest signal by using a second code when transmission data to betransmitted said base station occur, and also carries out a process oftransmitting said coded individual data by using said uplink commonchannel.
 10. A data communication method which is implemented by acommunication system provided with a base station which transmits databy using an OFDM (Orthogonal Frequency Division Multiplexing) method asa downlink access method, and a mobile terminal which transmits acontrol signal including a response signal corresponding to a result ofreception of the data transmitted from said base station to said basestation, and which transmits a scheduling request signal with which tomake a request for allocation of radio resources to said base stationbefore transmitting transmission data to said base station,characterized in that said mobile terminal carries out a control signalgeneration process of, when transmission data to be transmitted to saidbase station occur, performing time division multiplexing of at leastsaid scheduling request signal and said response signal to generate anuplink control signal, and a control signal transmission process oftransmitting a control signal including said uplink control signalgenerated through said control signal generation process to said basestation by using a random access channel which is a physical channel.11. A communications system provided with a base station which transmitsdata by using an OFDM (Orthogonal Frequency Division Multiplexing)method as a downlink access method, and a mobile terminal having afunction of receiving the data transmitted from said base station andtransmitting uplink data to said base station, characterized in thatsaid base station allocates mobile terminal identifying information usedfor transmitting a signal for measurement of uplink communicationquality to the mobile terminal when the mobile terminal is nottransmitting any uplink data in a state in which synchronization withsaid base station is established.
 12. A communications system providedwith a base station which transmits data by using an OFDM (OrthogonalFrequency Division Multiplexing) method as a downlink access method, anda mobile terminal having a function of receiving the data transmittedfrom said base station and transmitting uplink data to said basestation, characterized in that when the mobile terminal is nottransmitting any uplink data in a state in which synchronization withsaid base station is established, the mobile terminal transmits ascheduling request signal with which to make a request for allocation ofradio resources to said base station by using a signal for measurementof uplink communication quality.
 13. The communications system accordingto claim 12, characterized in that after transmitting the schedulingrequest signal to the base station by using the signal for measurementof uplink communication quality, the mobile terminal transmits thescheduling request signal to the base station again by using the signalfor measurement of uplink communication quality when recognizing that noallocation of radio resources thereto has been carried out by said basestation within a predetermined time interval.
 14. The communicationssystem according to claim 12, characterized in that after transmittingthe scheduling request signal to the base station by using the signalfor measurement of uplink communication quality, the mobile terminaltransmits the scheduling request signal to the base station continuouslyby using the signal for measurement of uplink communication qualityuntil allocation of radio resources thereto is carried out by said basestation.
 15. The communications system according to claim 12,characterized in that according to an instruction from the base station,the mobile terminal sets up a transmit frequency of the signal formeasurement of uplink communication quality which the mobile terminaluses for transmission of the scheduling request signal.
 16. Thecommunications system according to claim 15, characterized in that wheninstructing the mobile terminal to set up the transmit frequency of thesignal for measurement of uplink communication quality, the base stationdetermines the transmit frequency of the signal for measurement ofuplink communication quality by taking into consideration a number ofmobile terminals to which the base station currently allocates a band.17. The communications system according to claim 15, characterized inthat when instructing the mobile terminal to set up the transmitfrequency of the signal for measurement of uplink communication quality,the base station determines the transmit frequency of the signal formeasurement of uplink communication quality by taking into considerationdownlink communication quality which is notified thereto from saidmobile terminal.
 18. The communications system according to claim 12,characterized in that when transmitting the scheduling request signal tothe base station by using the signal for measurement of uplinkcommunication quality, the mobile terminal determines a transmitfrequency of said signal for measurement of uplink communicationquality.
 19. The communications system according to claim 18,characterized in that when determining the transmit frequency of thesignal for measurement of uplink communication quality, the mobileterminal measures downlink communication quality and determines thetransmit frequency of the signal for measurement of uplink communicationquality in consideration of said downlink communication quality.
 20. Acommunications system provided with a base station which transmits databy using an OFDM (Orthogonal Frequency Division Multiplexing) method asa downlink access method, and a mobile terminal having a function ofreceiving the data transmitted from said base station and transmittinguplink data to said base station, characterized in that when the mobileterminal is not transmitting any uplink data in a state in whichsynchronization with said base station is established, the mobileterminal transmits a scheduling request signal with which to make arequest for allocation of radio resources to said base station by usinga signal for measurement of uplink communication quality which themobile terminal transmits for uplink timing synchronization even duringa time interval during which the mobile terminal is not transmitting anyuplink data to said base station.
 21. The communications systemaccording to claim 20, characterized in that when transmitting thescheduling request signal to the base station by using the signal formeasurement of uplink communication quality, the mobile terminaldistinguishes a symbol pattern of said signal for measurement of uplinkcommunication quality from a symbol pattern of the signal formeasurement of uplink communication quality at a time when the mobileterminal does not use for transmission of the scheduling request signal.22. The communications system according to claim 20, characterized inthat when transmitting the signal for measurement of uplinkcommunication quality to the base station, the mobile terminal inserts asymbol indicating presence or absence of the scheduling request signalinto a symbol pattern of said signal for measurement of uplinkcommunication quality.
 23. The communications system according to claim20, characterized in that when transmitting the scheduling requestsignal to the base station by using the signal for measurement of uplinkcommunication quality, the mobile terminal uses mobile terminalidentifying information different from mobile terminal identifyinginformation which is allocated to transmission of the signal formeasurement of uplink communication quality.
 24. The communicationssystem according to claim 20, characterized in that when transmittingthe scheduling request signal to the base station by using the signalfor measurement of uplink communication quality, the mobile terminalmultiplies said signal for measurement of uplink communication qualityby a code different from a code by which the signal for measurement ofuplink communication quality at a time when the mobile terminal does notuse for transmission of the scheduling request signal is multiplied. 25.A communications system provided with a base station which transmitsdata by using an OFDM (Orthogonal Frequency Division Multiplexing)method as a downlink access method, and a mobile terminal having afunction of receiving the data transmitted from said base station andtransmitting uplink data to said base station, characterized in thatwhen the mobile terminal is not transmitting any uplink data in a statein which synchronization with said base station is established andaccepts a dedicated channel allocated thereto via which the mobileterminal transmits a response signal corresponding to a result ofreception of the data transmitted from said base station, the mobileterminal transmits a scheduling request signal with which to make arequest for allocation of radio resources to said base station by usinga signal for measurement of uplink communication quality.
 26. Acommunications system provided with a base station which transmits databy using an OFDM (Orthogonal Frequency Division Multiplexing) method asa downlink access method, and a mobile terminal having a function ofreceiving the data transmitted from said base station and transmittinguplink data to said base station, characterized in that when the mobileterminal is not transmitting any uplink data in a state in whichsynchronization with said base station is established and accepts adedicated channel allocated thereto via which the mobile terminaltransmits a response signal corresponding to a result of reception ofthe data transmitted from said base station, the mobile terminaltransmits a scheduling request signal with which to make a request forallocation of radio resources to said base station by using a signal formeasurement of uplink communication quality which the mobile terminaltransmits for uplink timing synchronization even during a time intervalduring which the mobile terminal is not transmitting any uplink data tosaid base station.
 27. A mobile terminal having a function of receivingdata transmitted from a base station which transmits the data by usingan OFDM (Orthogonal Frequency Division Multiplexing) method as adownlink access method, and transmitting uplink data to said basestation, characterized in that when said mobile terminal is nottransmitting any uplink data in a state in which synchronization withsaid base station is established, said mobile terminal transmits ascheduling request signal with which to make a request for allocation ofradio resources to said base station by using a signal for measurementof uplink communication quality.
 28. A mobile terminal having a functionof receiving data transmitted from a base station which transmits thedata by using an OFDM (Orthogonal Frequency Division Multiplexing)method as a downlink access method, and transmitting uplink data to saidbase station, characterized in that said mobile terminal transmits ascheduling request signal with which to make a request for allocation ofradio resources to said base station by using a signal for measurementof uplink communication quality which said mobile terminal transmits foruplink timing synchronization during a time interval during which saidmobile terminal is not transmitting any uplink data to said base stationin a state in which synchronization with said base station isestablished.
 29. A mobile terminal having a function of receiving datatransmitted from a base station which transmits the data by using anOFDM (Orthogonal Frequency Division Multiplexing) method as a downlinkaccess method, and transmitting uplink data to said base station,characterized in that when said mobile terminal is not transmitting anyuplink data in a state in which synchronization with said base stationis established and an exclusive channel via which said mobile terminaltransmits a response signal corresponding to a result of reception ofthe data transmitted from said base station is allocated thereto, saidmobile terminal transmits a scheduling request signal with which to makea request for allocation of radio resources to said base station byusing a signal for measurement of uplink communication quality.
 30. Amobile terminal having a function of receiving data transmitted from abase station which transmits the data by using an OFDM (OrthogonalFrequency Division Multiplexing) method as a downlink access method, andtransmitting uplink data to said base station, characterized in thatwhen said mobile terminal is not transmitting any uplink data in a statein which synchronization with said base station is established and anexclusive channel via which said mobile terminal transmits a responsesignal corresponding to a result of reception of the data transmittedfrom said base station is allocated thereto, said mobile terminaltransmits a scheduling request signal with which to make a request forallocation of radio resources to said base station by using a signal formeasurement of uplink communication quality which said mobile terminaltransmits for uplink timing synchronization during a time intervalduring which said mobile terminal is not transmitting any uplink data tosaid base station.